ASP.NET - Problema con Object reference no set....

Object reference not set to an instance of an object. ERROR...
Dejo subrayado y en negritas la linea de codigo en donde me genera el error si alguien me puede ayudar, lo agradecere de antemano..Gracias!.
Lenguage C#

Estoy trabajando en un proyecto ASP.....

using System;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Collections;
using System.Collections.Generic;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Text;
using System.Net;
using System.IO;

public partial class Index : System.Web.UI.Page
{
public string titulopagina, fecha1, rutam, carpeta, m0, m1, m2, m3, m4, m5, m6, m7,mSku,mPLM, varunoses, vardosses, vartresses, varcuatroses, varcincoses, varseisses, varsieteses, varochoses;
public int navega, gruponav;

private SqlConnection ConnSQLSV;
private SqlDataAdapter da;
private DataSet ds;

protected void Page_Load(object sender, EventArgs e)
{
string sCultura = HttpContext.Current.Request.UserLanguages[0].ToString().ToLower();

#region Cultura
//switch (sCultura.ToString())
//{
// case "es-mx":
// Session["SPais"] = 1;
// Session["SCulturaId"] = sCultura.ToString();
// break;
// case "es-gt":
// Session["SPais"] = 2;
// Session["SCulturaId"] = sCultura.ToString();
// break;
// case "es-hn":
// Session["SPais"] = 4;
// Session["SCulturaId"] = sCultura.ToString();
// break;
// case "es-pe":
// Session["SPais"] = 6;
// Session["SCulturaId"] = sCultura.ToString();
// break;
// default:
// Session["SPais"] = 1;
// Session["SCulturaId"] = "es-mx";
// break;
//}
#endregion
Session["SPais"] = "1";//Request.QueryString["PaisId"]; //Pais del Usuario
Session["SUsuario"] = "paraprueba"; //Usuario de Sesion
//Session["SNavUsuario"] = ""; //navegacion de Usuario
//Session["SError"] = ""; //Error de navegacion
//Session["SFlaVen"] = "null"; //Bandera de Vencimiento
//Session["SFechaVen"] = "null"; //Fecha de Vencimiento
//Session["SRol"] = "199"; //Rol Publico
//Session["FacUsuario"] = "999999"; //?
//Session["iTienda"] = "1"; //Bandera Si/No es Tienda
//Session["STiendaId"] = ""; //Tienda ID
Session["SModeloSearch"] = ""; //Modelo de Busqueda
//Session["SDesModeloSearch"] = ""; //
//Session["SRecordatrioVta"] = 0;
//Session["CSI_Clave"] = "";
//Session["SignMoneda"] = "";
//Session["IsMultiPais"] = "0";
//Session["SMotivoId"] = "";
//Session["SFlaAceites"] = "1";
//Session["SModeloAnio"] = DateTime.Now.Year.ToString();

if (!IsPostBack)
{
DataBind();

TextBox1.Text = "";

}

if (Page.Request.Form.Count > 0)
{
if (Page.Request.Form["IdUsuario"] != null)
{
varunoses = Page.Request.Form["IdUsuario"].ToString();
Session["SesUno"] = varunoses;
}
if (Page.Request.Form["IdUsuario"] != null)
{
vardosses = Page.Request.Form["Compania"].ToString();
Session["SesDos"] = vardosses;
}
if (Page.Request.Form["IdUsuario"] != null)
{
vartresses = Page.Request.Form["RolId"].ToString();
Session["SesTres"] = vartresses;
}
if (Page.Request.Form["IdUsuario"] != null)
{
varcuatroses = Page.Request.Form["RolDesc"].ToString();
Session["SesCuatro"] = varcuatroses;
}
if (Page.Request.Form["IdUsuario"] != null)
{
varcincoses = Page.Request.Form["IdiomaId"].ToString();
Session["SesCinco"] = varcincoses;
}
if (Page.Request.Form["IdUsuario"] != null)
{
varseisses = Page.Request.Form["DescIdioma"].ToString();
Session["SesSeis"] = varseisses;
}
if (Page.Request.Form["IdUsuario"] != null)
{
varsieteses = Page.Request.Form["Nombre"].ToString();
Session["SesSiete"] = varsieteses;

}
if (Page.Request.Form["IdUsuario"] != null)
{
varochoses = Page.Request.Form["PC"].ToString();
Session["SesOcho"] = varochoses;
}
}
else
{
if (Page.Request.Form["IdUsuario"] != null)
{
Page.Response.Redirect("AccesDenied.aspx");
}
}

if (Convert.ToInt32(Session["SesTres"]) == 2)
{
gruponav = 0;
}
else if (Convert.ToInt32(Session["SesTres"]) == 3)
{
gruponav = 1;
}
else
{
gruponav = 2;
}

DateTime now = DateTime.Now;
fecha1 = now.ToShortDateString();



if (Page.Request.QueryString.Count > 0)
{
string matsap;
matsap = Page.Request.QueryString["ReqMatSAP"];
ConsultaCat("sp_SIEITK_VisorRefacciones3 2,'" + matsap + "'");

}


}

public Index()
{
ConnSQLSV = new SqlConnection(ConfigurationManager.AppSettings.Get("CnxSIEITK").ToString());
}

private void ConsultaCat(string stored)
{
try
{
string command = stored;
da = new SqlDataAdapter(command, ConnSQLSV);
ds = new DataSet();
da.Fill(ds);

int cuantosreg;

cuantosreg = ds.Tables[0].Rows.Count;

if (cuantosreg == 0)
{
navega = 0;
Label1.Text = ":: SAP # requested is not available ::";
}
else if (cuantosreg == 1)
{
navega = 1;
m0 = ds.Tables[0].Rows[0][0].ToString();
m1 = ds.Tables[0].Rows[0][1].ToString();
m2 = ds.Tables[0].Rows[0][2].ToString();
m3 = ds.Tables[0].Rows[0][3].ToString();
m4 = ds.Tables[0].Rows[0][4].ToString();
m5 = ds.Tables[0].Rows[0][5].ToString();
m6 = ds.Tables[0].Rows[0][6].ToString();
m7 = ds.Tables[0].Rows[0][8].ToString();
mSku = ds.Tables[0].Rows[0][9].ToString();

String lkModelos = String.Empty;

foreach (DictionaryEntry de in this.ModelosToURL(m5))
{
lkModelos += "<a class=enlaceboton href=" + de.Value + ">" + de.Key + "</a> ";
}
m5 = lkModelos;

ImageA.ImageUrl = "ImagenCarga.aspx?ImageID=" + m0;
ImageA.AlternateText = m0.ToString();
//ImageB.ImageUrl = "ImagenCarga.aspx?ImageID=" + m0;
//ImageB.AlternateText = m0.ToString();
//ImageC.ImageUrl = "ImagenCarga.aspx?ImageID=" + m0;
//ImageC.AlternateText = m0.ToString();

Image6.ImageUrl = m7.ToString();
Image6.AlternateText = "group for: " + m0.ToString();
Image6.Visible = true;
Label3.Visible = true;
Image7.ImageUrl = m7.ToString();
Image7.AlternateText = "group for: " + m0.ToString();
Image7.Visible = true;
Label4.Visible = true;

string bloqueimg = m0.Substring(0, 1).ToString();

TRAInventario.BusinessLogic.CProducto BusquedaGeneral = new TRAInventario.BusinessLogic.CProducto();
BusquedaGeneral.cBusqueda = TextBox1.Text;
BusquedaGeneral.UserId = Session["SUsuario"].ToString();
BusquedaGeneral.modeloID = Session["SModeloSearch"].ToString();
BusquedaGeneral.PaisId = int.Parse(Session["SPais"].ToString());
DataSet dsInventario = new DataSet();
dsInventario = BusquedaGeneral.getItemProdInventoryRefacciones(BusquedaGeneral.getResultGeneral());
//dsInventario.Tables[0].Rows[0][0].ToString();

if (bloqueimg == "E")
{
carpeta = "ENGINE";
}
else
{
carpeta = "FRAME";
}

rutam = carpeta + "/" + m0.Substring(0, 3).ToString() + "/" + m0 + ".jpg";

}
else
{
for (int row = 0; row < ds.Tables[0].Rows.Count; row++)
{

m0 = ds.Tables[0].Rows[row][0].ToString();
m1 = ds.Tables[0].Rows[row][1].ToString();
m2 = ds.Tables[0].Rows[row][2].ToString();
m3 = ds.Tables[0].Rows[row][3].ToString();

string stiloUno;

if (row % 2 == 0)
{
stiloUno = " bgUnoFila";
}
else
{
stiloUno = " bgDosFila";
}


TableRow trFilaMotosProd = new TableRow();
trFilaMotosProd.CssClass = "gridfnt";
TableCell tr1c1 = new TableCell();
tr1c1.CssClass = "centro" + stiloUno + " negritas";
tr1c1.Width = 60;
TableCell tr1c2 = new TableCell();
tr1c2.CssClass = "izquierda" + stiloUno;
tr1c2.Width = 100;
tr1c1.Text = "<a href='Index.aspx?ReqMatSAP=" + m0 + "' target='_self'>" + m0 + "</a>";
tr1c2.Text = m1 + "<br />" + m2 + "<br />" + m3;
trFilaMotosProd.Cells.Add(tr1c1);
trFilaMotosProd.Cells.Add(tr1c2);
Table1.Rows.Add(trFilaMotosProd);
}


navega = 2;
}


}
catch (Exception ex)
{
ClientScript.RegisterStartupScript(typeof(Page), "AlertaFalla", "<script language=JavaScript>alert(':: Service not available ::<br />" + ex.ToString() + "');</script>");
}
finally
{
ds.Dispose();

if (ConnSQLSV.State != ConnectionState.Closed)
{
ConnSQLSV.Close();
}
}
}

protected void ImageButton1_Click(object sender, ImageClickEventArgs e)
{
Page.Response.Redirect("Index.aspx");
}
protected void ImageButton2_Click(object sender, ImageClickEventArgs e)
{
Page.Response.Redirect("imgspares/album-cs.aspx");
}
protected void ImageButton3_Click(object sender, ImageClickEventArgs e)
{
ConsultaCat("sp_SIEITK_VisorRefacciones2 2,'" + TextBox1.Text + "'");
}
protected void ImageButton4_Click(object sender, ImageClickEventArgs e)
{
if (Convert.ToInt32(Session["SesTres"]) == 3)
{
ClientScript.RegisterStartupScript(typeof(Page), "AdminPictures", "<script language=JavaScript>cambiaadmin();</script>");
}
else
{
ClientScript.RegisterStartupScript(typeof(Page), "AdminPicturesDenied", "<script language=JavaScript>alert('You are not granted to acces this module');</script>");
}
}
private Hashtable ModelosToURL(String _modelos)
{
String linksModelos = String.Empty;
Hashtable ht = new Hashtable();
foreach(char caracter in _modelos)
{
if (caracter.Equals(' '))
{
continue;
}
if(caracter.Equals(','))
{
ht.Add(linksModelos, "/SCV_ITK/Groups/" + linksModelos + "/E01.jpg");
linksModelos = String.Empty;
continue;
}
linksModelos+=caracter;
}
ht.Add(linksModelos, "/SCV_ITK/Groups/" + linksModelos + "/E01.jpg");
linksModelos = String.Empty;
return ht;
}

}

si es exactamente en esa linea de codigo, creo que no podria ser mas que la clave CnxSIEITK No esté definida en archivo web.config de la aplicacion, puedes poner a depurar y pararte en esa linea, y evaluar la expresion ConfigurationManager.AppSettings.Get("CnxSIEITK") a ver que te trae.

Saludos