Saludos Tengo este codigo que he revisado y se supone debe hacer lo que publico pero aun no logro nada!!
De poder identificar alguna falla y de podernos contactar es importante asi que $ Muchas Gracias!!

using System;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Collections.Generic;

using System.Text;

using System.Runtime.CompilerServices;

using System.Security;

using System.Security.Permissions;

using Microsoft.SharePoint;

using Microsoft.SharePoint.WebControls;

using System.Data.SqlClient;

using System.Data.OleDb;

using System.Configuration;

using System.Data;

using System.Linq;

using System.Web;

using System.Web.Security;

using System.Web.UI.HtmlControls;

using System.Net.Mail;

using System.Collections;

using System.Collections.Specialized;

using System.Reflection;

using System.Security.Principal;

using System.Net;

using System.Net.Mime;

using System.Xml.Serialization;

using System.Drawing;

using System.Text.RegularExpressions;

using Microsoft.SharePoint.WebPartPages;

using System.Runtime.InteropServices;

using System.DirectoryServices;

using System.Security.Cryptography;

using wsswebparts = Microsoft.SharePoint.WebPartPages;

using aspnetwebparts = System.Web.UI.WebControls.WebParts;

using System.ComponentModel;

using System.Collections.ObjectModel;

[assembly: AllowPartiallyTrustedCallers]



namespace Extranet_Materias

{

    public class Extranet_Materias : wsswebparts.WebPart, wsswebparts.ITransformableFilterValues

    {

        chla.DatosUsuario Dusuarios = new chla.DatosUsuario();

        GridView Grilla = new GridView();

        string _sErrDescription, mensaje, show,view;

        string[] choices = new string[5];



        protected DataTable GetDataTableFromQuery(string camlQry, SPList theList);

        //{   SPQuery listQry = new SPQuery();     listQry.Query = camlQry;   

    //    SPListItemCollection listItems = theList.GetItems(listQry);    

        return ListItems.GetDataTable(); } protected void BuildDataSet() {    

    //// get SPList objects for the lists in questions ... left as an exercise for the dev --

       //= "the CAML necessary to retreive the ites from list1";    

    //DataTable table1 = GetDataTable(camlQry, list1);     

    //table1.TableName = "Table1";    

     //DataTable table2 = GetDataTable(camlQry, list2);     

    //table1.TableName = "Table2";     

   // now build the DataSet   DataSet ds = new DataSet();     ds.Tables.Add(table1);    

    //ds.Tables.Add(table2);     ds.Tables.Add(table3);     

    //ds.Relations.Add("Table1_2", ds.Tables["Table1"].Columns["FieldA"], 

    //ds.Tables["Table2"].Columns["FieldA"]);     

    //ds.Relations.Add("Table2_3", ds.Tables["Table2"].Columns["FieldB"], 

    //ds.Tables["Table3"].Columns["FieldB"]);     

    //// now you can do something with these, like store them in the web part class 

    //and bind them to repeaters in the web part's Render() method } 



       

        public Extranet_Materias()

        {

            this.ChromeType = PartChromeType.BorderOnly;

            this.ExportMode = WebPartExportMode.All;

        }



        protected override void OnInit(EventArgs e)

        {

            try

            {

                this.ChromeType = PartChromeType.None;

                base.OnInit(e);

            }

            catch (Exception ex)

            {

                _sErrDescription = "  11 " + ex.Message;

            }



        }



        protected override void CreateChildControls()

        {

            try

            {

                base.CreateChildControls();

                Controls.Add(Grilla);

                Grilla.RowDataBound += new GridViewRowEventHandler(Grilla_RowDataBound);

                if (!Page.IsPostBack)

                    CargaInfo();

            }

            catch (Exception ex)

            {

                _sErrDescription += "   " + ex.Message;

            }

        }



        protected override void OnPreRender(EventArgs e)

        {

            Dusuarios = new chla.DatosUsuario();

            try

            {

                int i;

                GridViewRow row;

                Grilla.HeaderRow.Visible = false;

                for (i = 0; i < Grilla.Rows.Count; i++)

                {

                    row = Grilla.Rows[i];

                    if (row.RowType == DataControlRowType.DataRow)

                    {

                        string var;

                        string url = Dusuarios.UrlTop;



                        string Msg = row.Cells[1].Text;

                        string Password = "Academica";

                        string EncryptedString = EncryptString(Msg, Password);

                        string DecryptedString = DecryptString(EncryptedString, "Academica");

                        string varurl = HttpContext.Current.Request.QueryString["var"].Replace(" ", "+");



                        var = "  <a href='" + url + "Paginas/Asignaturas.aspx?mat=" + EncryptedString + "&var=" + varurl + "'>" + row.Cells[2].Text + "</a> ";

                        row.Cells[2].Font.Name = "Tahoma";

                        row.Cells[2].Font.Size = 8;

                        row.Cells[2].Text = var;

                    }

                }

            }

            //catch (Exception ex)

                catch (NullReferenceException ex)

            {

                _sErrDescription += " OnPreRender    " + ex.Message;

            }

        }



        void Grilla_RowDataBound(object sender, GridViewRowEventArgs e)

        {

            e.Row.Cells[0].Visible = false;

            e.Row.Cells[1].Visible = false;

        }

     

        protected override void Render(HtmlTextWriter writer)

        {

            try

            {

                Grilla.RenderControl(writer);

                writer.Write("</BR></BR>");

                //writer.Write(mensaje);

                if (Dusuarios.Usuario == "juanp.lozano" || Dusuarios.Usuario == "sharepoint.admin")

                {

                    writer.Write(_sErrDescription);

                    //writer.Write(show);

                }

            }

            catch (Exception error)

            {

                if (Dusuarios.Usuario == "juanp.lozano" || Dusuarios.Usuario == "sharepoint.admin")

                {

                    writer.Write(_sErrDescription + error);

                    //writer.Write(show);

                }

            }

        }



        private void CargaInfo()

        {

            string ins = Dusuarios.IdInscripcion;

            string var = HttpContext.Current.Request.QueryString["var"].Replace(" ", "+");

            try

            {

		string ins = Dusuarios.IdInscripcion;

		string var = HttpContext.current.Request.QueryString["var"].Replace(" ",)



            

 string DecryptedString = DecryptString(var, "Academica");



                string sqlAA = " SELECT  dbo.MSAsignaturas.AsignaturaURL, dbo.MateriaCurso.IdMateriaCurso,  ";

                sqlAA += " dbo.MSAsignaturas.AsignaturaEsp ";

                sqlAA += " FROM         dbo.InscripciónMateriaCurso INNER JOIN ";

                sqlAA += " dbo.MateriaCurso ON dbo.InscripciónMateriaCurso.IdMateriaCurso = dbo.MateriaCurso.IdMateriaCurso INNER JOIN ";

                sqlAA += " dbo.AsignaturaGrado ON dbo.MateriaCurso.IdAsignaturaGrado = dbo.AsignaturaGrado.IdAsignaturaGrado INNER JOIN ";

                sqlAA += " dbo.Asignaturas INNER JOIN ";

                sqlAA += " dbo.MSAsignaturas ON dbo.Asignaturas.IdMSAsignatura = dbo.MSAsignaturas.IdMSAsignatura ON  ";

                sqlAA += " dbo.AsignaturaGrado.IdAsignatura = dbo.Asignaturas.IdAsignatura INNER JOIN ";

                sqlAA += " dbo.MSMaterias ON dbo.AsignaturaGrado.IdMSMateria = dbo.MSMaterias.IdMSMateria INNER JOIN ";

                sqlAA += " dbo.Inscripción ON dbo.InscripciónMateriaCurso.IdInscripción = dbo.Inscripción.IdInscripción INNER JOIN ";

                sqlAA += " dbo.Alumnos ON dbo.Inscripción.IdAlumno = dbo.Alumnos.IdAlumno INNER JOIN ";

                sqlAA += " dbo.Empleados ON dbo.MateriaCurso.IdProfesor = dbo.Empleados.IdEmpleado ";

                sqlAA += " WHERE     (dbo.MateriaCurso.Año = dbo.YearActual()) AND (dbo.Inscripción.IdInscripción = " + DecryptedString + ") ";

                sqlAA += " ORDER BY dbo.MSAsignaturas.AsignaturaEsp ";



                mensaje = "" + sqlAA;

                show = "" + sqlAA; 



                DataSet DS_AA = Dusuarios.DameAllDatos(sqlAA);



                Grilla.DataSource = DS_AA;

                Grilla.DataBind();

                Grilla.Font.Name = "Tahoma";

                Grilla.Font.Size = 8;

                Grilla.BorderColor = System.Drawing.Color.Black;

                Grilla.GridLines = GridLines.None;

                DS_AA.Dispose();





            }

            catch (Exception error)

            {

                _sErrDescription += "<b>Error</b>"+ error;

            }

        }



        public static string EncryptString(string Message, string Passphrase)

        {

            byte[] Results;

            System.Text.UTF8Encoding UTF8 = new System.Text.UTF8Encoding();



            // Step 1. We hash the passphrase using MD5

            // We use the MD5 hash generator as the result is a 128 bit byte array

            // which is a valid length for the TripleDES encoder we use below



            MD5CryptoServiceProvider HashProvider = new MD5CryptoServiceProvider();

            byte[] TDESKey = HashProvider.ComputeHash(UTF8.GetBytes(Passphrase));



            // Step 2. Create a new TripleDESCryptoServiceProvider object

            TripleDESCryptoServiceProvider TDESAlgorithm = new TripleDESCryptoServiceProvider();



            // Step 3. Setup the encoder

            TDESAlgorithm.Key = TDESKey;

            TDESAlgorithm.Mode = CipherMode.ECB;

            TDESAlgorithm.Padding = PaddingMode.PKCS7;



            // Step 4. Convert the input string to a byte[]

            byte[] DataToEncrypt = UTF8.GetBytes(Message);



            // Step 5. Attempt to encrypt the string

            try

            {

                ICryptoTransform Encryptor = TDESAlgorithm.CreateEncryptor();

                Results = Encryptor.TransformFinalBlock(DataToEncrypt, 0, DataToEncrypt.Length);

            }

            finally

            {

                // Clear the TripleDes and Hashprovider services of any sensitive information

                TDESAlgorithm.Clear();

                HashProvider.Clear();

            }

            // Step 6. Return the encrypted string as a base64 encoded string

            return Convert.ToBase64String(Results);

        }



        public static string DecryptString(string Message, string Passphrase)

        {

            byte[] Results;

            System.Text.UTF8Encoding UTF8 = new System.Text.UTF8Encoding();

            // Step 1. We hash the passphrase using MD5

            // We use the MD5 hash generator as the result is a 128 bit byte array

            // which is a valid length for the TripleDES encoder we use below        

            MD5CryptoServiceProvider HashProvider = new MD5CryptoServiceProvider();

            byte[] TDESKey = HashProvider.ComputeHash(UTF8.GetBytes(Passphrase));

            // Step 2. Create a new TripleDESCryptoServiceProvider object

            TripleDESCryptoServiceProvider TDESAlgorithm = new TripleDESCryptoServiceProvider();

            // Step 3. Setup the decoder

            TDESAlgorithm.Key = TDESKey;

            TDESAlgorithm.Mode = CipherMode.ECB;

            TDESAlgorithm.Padding = PaddingMode.PKCS7;

            // Step 4. Convert the input string to a byte[]

            byte[] DataToDecrypt = Convert.FromBase64String(Message);

            // Step 5. Attempt to decrypt the string

            try

            {

                ICryptoTransform Decryptor = TDESAlgorithm.CreateDecryptor();

                Results = Decryptor.TransformFinalBlock(DataToDecrypt, 0, DataToDecrypt.Length);

            }

            finally

            {

                // Clear the TripleDes and Hashprovider services of any sensitive information

                TDESAlgorithm.Clear();

                HashProvider.Clear();

            }

            // Step 6. Return the decrypted string in UTF8 format

            return UTF8.GetString(Results);

        }



        [wsswebparts.WebPartStorage(wsswebparts.Storage.Shared)]

        public virtual bool AllowMultipleValues

        {

            get

            {

                return true;

            }

        }



        [wsswebparts.WebPartStorage(wsswebparts.Storage.None)]

        public virtual bool AllowAllValue

        {

            get

            {

                return true;

            }

        }



        [wsswebparts.WebPartStorage(wsswebparts.Storage.None)]

        public virtual bool AllowEmptyValue

        {

            get

            {

                return false;

            }

        }



        [wsswebparts.WebPartStorage(wsswebparts.Storage.None)]

        public virtual string ParameterName

        {

            get

            {

                return "Escuela";

            }

        }



        [wsswebparts.WebPartStorage(wsswebparts.Storage.None)]

        public virtual ReadOnlyCollection<string> ParameterValues

        {

            get

            {

                string[] values = this.Dato_();

                return values == null ?

                    null :

                    new ReadOnlyCollection<string>(values);

            }

        }



        public string[] Dato_()

        {



            try

            {

                string var = HttpContext.Current.Request.QueryString["var"].Replace(" ", "+");

                //var = "VrXb3ktS42k=";



                string DecryptedString = DecryptString(var, "Academica");



                string sql_filtro = "SELECT CódigoMSCurso FROM  dbo.Inscripción WHERE (IdInscripción = " + DecryptedString + ")";

                DataSet Datos_alum = Dusuarios.DameAllDatos(sql_filtro);

                string oCurso = Datos_alum.Tables[0].Rows[0]["CódigoMSCurso"].ToString();

                Datos_alum.Dispose();



                string escuela;

                try

                {

                    int curso = int.Parse((oCurso).Substring(0, 2));

                    if ((curso >= 6) && (curso < 9)) escuela = "Escuela media";

                    else if (curso >= 9) escuela = "Bachillerato";

                    else if ((curso >= 1) && (curso <= 5)) escuela = "Primaria";

                    else escuela = "Preescolar";

                }

                catch

                {

                    escuela = "Preescolar";

                }





                choices[0] = escuela;

            }

            catch (Exception error)

            {

                _sErrDescription += "Dato_ " + error.Message;

            }

            return choices;

        }



        [aspnetwebparts.ConnectionProvider("Filtro Lista",

               "ITransformableFilterValues", AllowsMultipleConnections = true)]

        public wsswebparts.ITransformableFilterValues

        SetConnectionInterface()

        {

            return this;

        }

    }

}