导出pdf出错

错误如下：
[COMException (0x800002b4): 
文件 C:\DOCUME~1\JABC\ASPNET\LOCALS~1\Temp\R8112List2 {22596C4D-20FF-4C61-9591-E8E527D0F08B}.rpt 内出错：
无效导出 DLL 或导出格式。]
   CrystalDecisions.ReportAppServer.Controllers.ReportSourceClass.Export(ExportOptions pExportOptions, RequestContext pRequestContext) +0
   CrystalDecisions.ReportSource.EromReportSourceBase.ExportToStream(ExportRequestContext reqContext) +260[InvalidArgumentException: 
文件 C:\DOCUME~1\JABC\ASPNET\LOCALS~1\Temp\R8112List2 {22596C4D-20FF-4C61-9591-E8E527D0F08B}.rpt 内出错：
无效导出 DLL 或导出格式。]代码： ReportDocument reportDoc = new ReportDocument();
            if (fileType == "PdfList")
            {
                reportDoc.Load(Server.MapPath("R8112List2.rpt"));
            }
            else
            {
                reportDoc.Load(Server.MapPath("R8112Cost.rpt"));                            
            }
            DataSet dsrpt = new DataSet();
            dsrpt = getRptDs(TxbBomNo.Text.Trim());//取得数据
            reportDoc.SetDataSource(dsrpt);
            //生成文件
            string fileUrl = "";
            DiskFileDestinationOptions objFile = new DiskFileDestinationOptions();
            ExportOptions objExport = reportDoc.ExportOptions;
            objExport.ExportDestinationOptions = objFile;
            objExport.ExportDestinationType = ExportDestinationType.DiskFile;
            switch (fileType)
            {
                case "Pdf":
                    Response.ContentType = "application/pdf";
                    objExport.ExportFormatType = ExportFormatType.PortableDocFormat;
                    objFile.DiskFileName = Server.MapPath("~/SCFOLDER/PRINT/R8112.pdf");
                    fileUrl = "~/SCFOLDER/PRINT/R8112.pdf";
                    break;
                case "Doc":
                    Response.ContentType = "application/ms-excel";
                    objExport.ExportFormatType = ExportFormatType.WordForWindows;
                    objFile.DiskFileName = Server.MapPath("~/SCFOLDER/PRINT/R8112.doc");
                    fileUrl = "~/SCFOLDER/PRINT/R8112.doc";
                    break;
                case "Xls":
                    Response.ContentType = "application/vnd.ms-excel";
                    objExport.ExportFormatType = ExportFormatType.Excel;
                    objFile.DiskFileName = Server.MapPath("~/SCFOLDER/PRINT/R8112.xls");
                    fileUrl = "~/SCFOLDER/PRINT/R8112.xls";
                    break;
            }
            
            reportDoc.Export();
          Response.Redirect(fileUrl);