Hey Bro,
You need to use <form> at starting of your Application i.e. <form> tag should be congaing the Grid.
Apply this at the starting of your application:-
<form id="form1" runat="server">
also don't forget to close this form at end of your Application.
Your code will look like this:
<form id="form1" runat="server">
<grid---->
----
----
---
</grid>
</form>