"File Not Found" issue

Hello.

We're experiencing an issue with an older application of ours when trying to merge a dynamic pdf into another one.  The pdf we're trying to merge successfully exists, however, I receive the following error when merging:
------------------------------------
Index was outside the bounds of the array.Stack: at aq.e(Stream A_0)
at aq..ctor(PdfDocument A_0, ae A_1)
at ceTe.DynamicPDF.Merger.PdfDocument.c()
at ceTe.DynamicPDF.Merger.PdfDocument..ctor(ap A_0, String A_1)
at ceTe.DynamicPDF.Merger.PdfDocument..ctor(String filePath)
at ceTe.DynamicPDF.Merger.MergeDocument..ctor(String filePath)
at AdworksControls.ReportHandler.IOAdCopyPDF(Int32 IOID, Int32 Company_Id,
String AdCopyPDFFileName)
-----------------------------------

The code causing the issue is as follows:
----------------------------------------------
ceTe.DynamicPDF.Merger.MergeDocument pdfMerge = new MergeDocument(refPage.Server.MapPath(AdCopyPDFFileName));

System.IO.Stream pdfStream = new System.IO.MemoryStream();
                                pdfMerge.Draw(pdfStream);
                                return pdfStream;
----------------------------------------------------

Any idea what may be causing this? 
Thanks

Hello,

Can you please send over the following details to our support team at:support@cete.com so that they can look into it further?

1.Input PDF document with which you are getting error.
2.Exact version and build number of the DynamicPDF dll file which you are using in your application.

Thanks,
ceTe Software Support Team.