Export DataGrid to Excel

con.Open();
Response.Clear();
Response.AddHeader("content-disposition", "attachment;filename=FileName.xls");
Response.Charset = "";
Response.ContentType = "application/Excel";
//Response.ContentType = "application/vnd.xls";
System.IO.StringWriter stringWrite = new System.IO.StringWriter();
System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
DataGrid1.RenderControl(htmlWrite);
Response.Write(stringWrite.ToString());
Response.End();
con.Close();