asp page design view is not showing gridview on design page.

I am working on a asp project. one of the asp page is not showing it's design view completely but it showing it's source view and code is running fine.                                         actually gridview is not showing in design view. please help me to fix it.
following is my code please go through it
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="inassembly.aspx.vb" Inherits="inassembly" %> <!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="Head1" runat="server">     <link rel="shortcut icon" type="image/x-icon" href="Images/fa ...