i wanted to open modal up using ajax,gridview and detail view but its not opening

see teh code here
Code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Configuration;
using System.Data.SqlClient;
using System.Data;


//http://mattberseth.com/blog/2008/04/masterdetail_with_the_gridview.html

public partial class GRIDVIEW_DetailView : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void Customer_Selected(Object sender, GridViewCommandEventArgs e)
    {


    }



    protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
    {

    }
    protected void gvCustomers_SelectedIndexChanged(object sender, EventArgs e)
    {
        this.dvCustomerDetail.Visible = true;
        ExecuteTSQL ts = new ExecuteTSQL();
        string s = this.gvCustomers.SelectedRow.DataItemIndex.ToString();
        string s1 = this.gvCustomers.SelectedValue.ToString();

        DataSet ds = new DataSet();
        ds = ts.SelectQueryDS("select * from orders where customerid=" + "'" + s1 + "'");
        this.dvCustomerDetail.DataSource = ds;
        this.DataBind();



        this.mdlPopup.Show();

    }
    protected void gvCustomers_RowCommand(object sender, GridViewCommandEventArgs e)
    {

    }
}

Code:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="GRIDVIEW_DetailView.aspx.cs" Inherits="GRIDVIEW_DetailView" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="head" runat="server">
    <title>Master Details Example</title>
    <script runat="server">
  
    
    /// <summary>
    /// 
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void BtnViewDetails_Click(object sender, EventArgs e)
    {
        //  get the gridviewrow from the sender so we can get the datakey we need
        Button btnDetails = sender as Button;
        GridViewRow row = (GridViewRow)btnDetails.NamingContainer;
        
        //  extract the customerid from the row whose details button originated the postback.
        //  grab the customerid and feed it to the customer details datasource
        //  finally, rebind the detailview
        //this.sqldsCustomerDetails.SelectParameters.Clear();
        //this.sqldsCustomerDetails.SelectParameters.Add("customerid", Convert.ToString(this.gvCustomers.DataKeys[row.RowIndex].Value));
        //this.dvCustomerDetail.DataSource = this.sqldsCustomerDetails;
        //this.dvCustomerDetail.DataBind();

        ////  update the contents in the detail panel
        //this.updPnlCustomerDetail.Update();
        ////  show the modal popup
        //this.mdlPopup.Show();
    }   
    
    </script>
 
</head>

<body>
    <form id="form1" runat="server">
     <asp:ToolkitScriptManager ID="toolkitScriptMaster" runat="server">
</asp:ToolkitScriptManager>
      <div>
            <asp:SqlDataSource ID="sqldsCustomers" runat="server" 
                
                SelectCommand="select customerid, companyname, contactname, contacttitle from customers" 
                ConnectionString="<%$ ConnectionStrings:renaConnectionString %>" />
            
           <%-- <p style="background-color:AliceBlue; width:95%">
                Example of using a ModalPopupExtender to edit the indivdual rows of a GridView.<br />
                To test out the functionality, click the Details button of any of the rows and watch what happens.<br />
            </p>--%>
            
            <br />
            <asp:UpdatePanel ID="updatePanel" runat="server" UpdateMode="Conditional">
                <ContentTemplate>            
                    <asp:Label ID="lblTitle" runat="server" Text="Customers" BackColor="lightblue" Width="95%" />
                    <asp:GridView 
                        ID="gvCustomers" runat="server" DataKeyNames="customerid" AutoGenerateColumns="False" 
                        AllowPaging="True" AllowSorting="True" DataSourceID="sqldsCustomers" 
                        Width="95%" onselectedindexchanged="gvCustomers_SelectedIndexChanged" 
                        onrowcommand="gvCustomers_RowCommand">
                        <AlternatingRowStyle BackColor="aliceBlue" />
                        <HeaderStyle HorizontalAlign="Left" />
                        <Columns>
                            <asp:BoundField DataField="customerid" HeaderText="customerid" 
                                SortExpression="customerid" ReadOnly="true" />
                            <asp:BoundField DataField="companyname" HeaderText="companyname" 
                                SortExpression="companyname" />
                            <asp:BoundField DataField="contactname" HeaderText="contactname" 
                                SortExpression="contactname" />
                            <asp:BoundField DataField="contacttitle" HeaderText="contacttitle" 
                                SortExpression="contacttitle" />     
                                <asp:TemplateField>
                                <ItemTemplate>
                                <asp:LinkButton id=btnviewdetails runat=server CommandArgument=customerid Text=edit CommandName=select>
                                </asp:LinkButton>
                                </ItemTemplate>
                                
                                </asp:TemplateField>           
                        </Columns>                    
                    </asp:GridView>
                </ContentTemplate>
            </asp:UpdatePanel>                    
            
     <%--             --%>     
            <asp:Panel ID="pnlPopup" runat="server" Width="500px" style="display:none">
                <asp:UpdatePanel ID="updPnlCustomerDetail" runat="server" UpdateMode="Conditional">
                    <ContentTemplate>
                       <asp:Button id="btnShowPopup" runat="server" style="display:none" />
            <asp:ModalPopupExtender 
                ID="mdlPopup" runat="server" TargetControlID="btnShowPopup" PopupControlID="pnlPopup" 
                CancelControlID="btnClose" />
                 <asp:DetailsView Visible=false ID="dvCustomerDetail" runat="server" DefaultMode="Edit" Width="95%" BackColor="white">
                  
                   </asp:DetailsView> 
                   
                <asp:LinkButton id=btnclose CausesValidation=false runat=server>
                
                
                </asp:LinkButton>
                </ContentTemplate>
                </asp:UpdatePanel>
                </asp:Panel>
          
                 
        </div>

    </form>
</body>
</html>
please do let me know if need further description of problem