export data in excel in single sheet

protected void exporttoexcel_Click(object sender, EventArgs e)

{Response.Clear();

Response.Buffer = true;

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

Response.ContentEncoding = System.Text.Encoding.UTF7;

Response.AddHeader("Content-Disposition", "attachment;filename=report.xls");

Response.Charset = "";

this.EnableViewState = false;

System.IO.StringWriter oStringWriter = new System.IO.StringWriter();

System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);

rpt.RenderControl(oHtmlTextWriter);

Response.Write(oStringWriter.ToString());

Response.End();

}