I try to export information to CSV but when i open the CSV it contains the CSV elements and complete page. Does anybody know wat could be the problem?:

The control contains:
<asp:LinkButton ID="lnkExport" runat="server" Text="Export" CssClass="dnnPrimaryAction" OnClick="lnkExport_Click" /> 

The lnkExport_Click code contains:

protected void lnkExport_Click(object sender, EventArgs e)
        {
            try
            {
                int ReportID = 1;
                ImportReportInfo report = ImportReportController.Get(this.PortalId, ReportID);
                if (report != null)
                {
                    ArrayList importedUsers = ImportedUserController.ListByReportID(this.PortalId, ReportID);
                    string ResultString = "";
                    foreach (ImportedUserInfo user in importedUsers)
                    {
                        ResultString += user.Username + "," + user.Firstname + "," + user.Lastname + "," + user.Street + "," + user.City + "," + user.Country + "," + user.Email + "," + user.ImportStatus + "," + user.ImportDate + "," + Environment.NewLine;
                    }
                    string fileName = String.Format("import report-{0}.csv", report.ReportDate.ToString("yyyy-MMM-dd-HHmmss"));

                    System.Web.HttpResponse Response = System.Web.HttpContext.Current.Response;

            byte[] lstByte = System.Text.Encoding.UTF8.GetBytes(Result);

            Response.ClearHeaders();
            Response.ClearContent();
            Response.ContentType = string.Format("{0}; charset=utf-8", ContentType);
            Response.AppendHeader("Content-disposition", string.Format("attachment; filename=\"{0}\"", FileName));
            Response.AppendHeader("Content-Length", lstByte.Length.ToString());
            Response.BinaryWrite(lstByte);
            Response.Flush();
            Response.End();
                }
            }
            catch (Exception exc)
            {
                Exceptions.ProcessModuleLoadException(this, exc);
            }
        }