Warning[] warnings;
                string[] streamids;
                string mimeType;
                string encoding;
                string extension;
 
                byte[] bytes = rptView.ServerReport.Render(
                   "Excel", null, out mimeType, out encoding, out extension,
                   out streamids, out warnings);
 
                System.IO.FileStream fs = new System.IO.FileStream(saveFileDialog1.FileName, System.IO.FileMode.Create);
                fs.Write(bytes, 0, bytes.Length);
                fs.Close();