WEB entwicklung, probleme mit GridView

using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Configuration;
//using System.Web.UI.WebControls;
using System.Drawing;
using System.IO;
using System.Data;


public partial class MainSite : System.Web.UI.Page
{
    ConnectionStringSettings connectionInfo;
    DataTable datTable;
    List<ProduktAktion> aktList;
    Image noPicture;


    protected class ProduktAktion
    {
        Image picture { get; set; }
        String description { get; set; }
        String mixes { get; set; }
        String unit { get; set; }
        String price_original { get; set; }
        String price_aktion { get; set; }


        protected internal ProduktAktion(Image new_pic, String new_desc, String new_mixes, String new_unit, String new_price_or, String new_price_akt)
        {
            picture = new_pic; description = new_desc; mixes = new_mixes; unit = new_unit; price_original = new_price_or; price_aktion = new_price_akt;
        }

    }


    protected void Page_Load(Object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
            GridViewAktion.DataBind();
    }

    protected void GridView_Load(object sender, EventArgs e)
    {
        noPicture = Image.FromFile(@"C:\Users\Thomas\Documents\Visual Studio 2010\WebSites\SchTeddUndMehr\noImage.bmp");
        aktList = new List<ProduktAktion>();
        connectionInfo = ConfigurationManager.ConnectionStrings['RefToDatabase'];
        SqlConnection connection = new SqlConnection(connectionInfo.ConnectionString);


        SqlCommand selectCommand = new SqlCommand("select Bild, Beschreibung, Menge, Einheit, Preis_netto, Rabatt, MWST, Aktion, Aktiv from Produkte", connection);


        selectCommand.Connection.Open();


        SqlDataReader dataReader = selectCommand.ExecuteReader();


        double dnormalPrice;
        decimal normalPrice, aktionPrice;


        Image aPic = null;


        datTable = new DataTable();
        datTable.Columns.Add("Bild");
        datTable.Columns.Add("Beschreibung");
        datTable.Columns.Add("Menge");
        datTable.Columns.Add("Einheit");
        datTable.Columns.Add("Preis normal");
        datTable.Columns.Add("Preis jetzt");


        while (dataReader.Read())
        {
            if ((bool)dataReader['Aktion'] && (bool)dataReader['Aktiv'])
            {
                dnormalPrice = (double)dataReader['Preis_netto'] * ((((double)(int)dataReader['MWST']) / 100) + 1);
                normalPrice = (decimal)dnormalPrice;
                aktionPrice = (decimal)(dnormalPrice - (dnormalPrice * (double)dataReader['Rabatt'] / 100));

                if (System.DBNull.Value != dataReader['Bild'])
                {
                    Byte[] bytePic = new Byte[0];
                    bytePic = (Byte[])dataReader['Bild'];
                    MemoryStream streamPic = new MemoryStream(bytePic);
                    aPic = Image.FromStream(streamPic);
                }
                else
                    aPic = noPicture;


                DataRow newRow = datTable.NewRow();
                newRow['Bild'] = aPic;
                newRow['Beschreibung'] = dataReader['Beschreibung'].ToString();
                newRow['Menge'] = String.Format("{0:f}", (double)dataReader['Menge']);
                newRow['Einheit'] = dataReader['Einheit'].ToString();
                newRow['Preis normal'] = normalPrice.ToString("C2", new System.Globalization.CultureInfo("de-DE"));
                newRow['Preis jetzt'] = aktionPrice.ToString("C2", new System.Globalization.CultureInfo("de-DE"));


                datTable.Rows.Add(newRow);

                //aktList.Add(new ProduktAktion(noPicture, dataReader['Beschreibung'].ToString(), String.Format("{0:f}", (double)dataReader['Menge']), dataReader['Einheit'].ToString(), normalPrice.ToString("C2", new System.Globalization.CultureInfo("de-DE")), aktionPrice.ToString("C2", new System.Globalization.CultureInfo("de-DE"))));
            }
        }

        dataReader.Close();
        connection.Close();


        GridViewAktion.DataSource = datTable;
        GridViewAktion.DataBind();



    }


    protected void ButtAktion_Click(object sender, EventArgs e)
    {


    }
}