Export To Excel in Sharepoint

Today I have facing problem in my user control web part when i exported grid view data into excel.

Error is like "control not load at form server tag".

I have created new ASPX page and generate grid and write code for export to excel.
After put this control into sharepoint 12 hive folder like "_Layout".

I have added Page View web part in page and added property link like "http://localhost/_layout/exportToExcel.aspx".

So its working fine.
Put following code in ASPX page.

public override void VerifyRenderingInServerForm(Control control)

{

}