ExportToHttpResponse method in crystal report not working...

Hello,

                        ABC.SetDataSource(objQueryProcess.ResultSet);
                        CrystalReportViewer1.ReportSource = ABC;
 ABC.ExportToHttpResponse(ExportFormatType.PortableDocFormat, Response, true, "Dividend Warrant"); // EXPORT TO PDF FORMAT 

HERE ABOVE MY EXPORTTOHTTPRESPONSE METHOD IS NOT WORKING....AFTER THIS IT GOES INTO THE CATCH BLOCK WHERE I GET EXCEPTION : Unable to evaluate expression because the code is optimized or a native frame is on top of the call stack.

I QUESTION IS WHY DOES THE REPORT DOES NOT GET EXPORTED TO THE PDF FORMAT???? WHERE AM I GOING WRONG?


THANKS!

Best Regards,
Rohan Laghate