Web Forms :: Exporting Page To Excel 2007

 I need to export asp.net page toexcel 2007. when i wrote the code as below:

protected void Button2_Click(object sender, EventArgs e) {Response.Clear();
Response.AddHeader("content-disposition", "attachment;filename=FileName.xls");
Response.Charset = ""; Response.ContentType = "application/vnd.xls"; System.IO.StringWriter string
Write = new System.IO.StringWriter(); System.Web.UI.HtmlTextWriter html
Write = new HtmlTextWriter(stringWrite); div1.RenderControl(htmlWrite);
Response.Write(stringWrite.ToString()); Response.End(); } 
publicoverride void VerifyRenderingInServerForm(Control control) {　　　
} and

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="poprint.aspx.cs" Inherits="print_poprint" EnableEventValidation="false" %>

It displays message as shown

The file you are trying to open is in a different format than specified by the file extension. Verify that the file is not corrupted and is from a trusted source before opening the file. Do you want to open the file now?

When yes is clicked it opens in excel but in some other format I think for I cannot AUTOSUM or sum the values result always as zero for numbers appears as text as " 222" . even if i try to format cells with numbers it does not works.