PDF fails to convert to PNG (result blank)

Hello, I have encountered a problem using ComponentPro.Pdf library. I am trying to convert a PDF file into a PNG and using your sample project “PDF to Image” I have found several PDF files that failed to convert. I have tried various modifications to the example code, but failed to get anything but a blank PNG file. In the process I have also found out that the PDF files that fail the conversion cannot be opened using the ComponentPro.PdfViewer (tested with “ViewerDemo” sample project). Is there any fix, or a work-around, to avoid this issue? Is there a specific property or something, that prevents PDF files from working properly witf the PDF component? The PDF files that don't work were generated by Catia V5, but most files generated by Catia work properly. I have sent an e-mail at support@componentpro.com 03.12.2019 with a pdf file that has this problem. Thank you