ASP.NET Exporting To Excel - Basic Error

The code below (partial) should export a file as Excel when the button near the bottom is clicked. The example I pulled the concept from uses a GridView for binding. I don't need to display it, just export it, so I created ExcelGrid visible=false at the bottom. The Response.Write(strQuery); is never getting executed. I get:

Exception Details: System.Web.HttpException: Control 'ExcelGrid' of type 'GridView' must be placed inside a form tag with runat=server.

I'm almost positive (from what you see below) that my ExcelGrid is inside the form tag, which contains the runat=server.

Any ideas? It works when you pull that code and just run the rest of the form so the runat=server is working for all of the other controls! Code: