lสอบถามเกี่ยวกับการ Export ออกมาเป็น Excel หน่อยคับว่าค่าตัวเลขข้างใน

               gvStaff.DataBind();
                string filename = "Staff.xls";
                System.IO.StringWriter tw = new System.IO.StringWriter();
                System.Web.UI.HtmlTextWriter hw = new System.Web.UI.HtmlTextWriter(tw);
                DataGrid dgGrid = new DataGrid();

                dgGrid.DataSource = ViewState["ds"];
                dgGrid.DataBind();

                //Get the HTML for the control.
                dgGrid.RenderControl(hw);
                //Write the HTML back to the browser.
                Response.ContentType = "application/vnd.ms-excel";
                string head = "<meta http-equiv='Conten-type' content ='text/html; charset=utf-8'>";
                Response.Charset = "UTF-8";
                Response.AppendHeader("Content-Disposition", "attachment; filename=" + filename + "");
                this.EnableViewState = false;
                Response.Write(head+tw.ToString());
                Response.End();