asp.net中用文件流方式下载文件，后台代码无错，前台浏览器没有下载反应？

string filename = context.Request["fileName"].ToString();
                string fileName = "【下载】" + filename;//客户端保存的文件名
                string filePath = System.Web.HttpContext.Current.Request.MapPath("~/UpFile/TraceCode/" + filename + "");//路径
                FileStream fileStream = new FileStream(filePath, FileMode.Open);
                byte[] bytes = new byte[(int)fileStream.Length];
                fileStream.Read(bytes, 0, bytes.Length);
                fileStream.Close();
                System.Web.HttpContext.Current.Response.ContentType = "application/octet-stream";
                System.Web.HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);
                System.Web.HttpContext.Current.Response.BinaryWrite(bytes);
                System.Web.HttpContext.Current.Response.Flush();
               //System.Web.HttpContext.Current.Response.End();
                //System.Web.HttpContext.Current.Response.Close();
                System.Web.HttpContext.Current.ApplicationInstance.CompleteRequest();