export to excel

I have a gried view data.

on export to excel click it return only

Here is my code.

Response.Clear();

Response.Buffer = true;

Response.ClearContent();

Response.ClearHeaders();

Response.Charset = "";

string FileName = "StockinhandDetails" + DateTime.Now + ".xls";

StringWriter strwritter = new StringWriter();

HtmlTextWriter htmltextwrtter = new HtmlTextWriter(strwritter); here return data

Response.Cache.SetCacheability(HttpCacheability.NoCache);

Response.ContentType = "application/ms-excel";

Response.AddHeader("Content-Disposition", "attachment;filename=" + FileName);

smallbanner1.GridLines = GridLines.Both;

smallbanner1.HeaderStyle.Font.Bold = true;

smallbanner1.RenderControl(htmltextwrtter);

Response.Write(strwritter.ToString());

Response.End();

Please help.