Ajax toolkit-ModalPopup Extender

hello i am new in asp.net and working on my first project and facing problem on modalpopupextender.

My thread-

When ever i set the properties of modalpopupextender it goes invisible from my design page.

when i debug the project and click on link button it shows nothing .

I need modalpopup extender for login but it is not working . I am using it on my Master Page.

Please help me

Thanks in advance....

code-

<%@ Page Language="VB" MasterPageFile="~/MasterPage.master" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" title="Untitled Page" %>

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">

    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
   
    <asp:LinkButton ID="LinkButton1" runat="server">LinkButton</asp:LinkButton>
   
   
    <asp:Panel ID="Panel1" runat="server">
    <div style="font-family: Andalus; font-size: x-large; color: #000000">Login</div>
        Email-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <br />
        Password-<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
        <br />
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        <asp:Button ID="Button1" runat="server" Text="Login" />
        &nbsp;&nbsp;&nbsp;&nbsp;
        <asp:Button ID="Button2" runat="server" Text="Cancel" />
    
    </asp:Panel>
    <asp:ModalPopupExtender ID="ModalPopupExtender1" runat="server"
        CancelControlID="Button2" OkControlID="Button1" onokscript="onOk()"
        PopupControlID="Panel1" TargetControlID="LinkButton1">
    </asp:ModalPopupExtender>
   
</asp:Content>