Can't print/save pdf files

We have a Lotus Notes database that contains code that uses COM to configure PDFCreator (sets auto-save folder and filename) and print documents.  On one computer this all works great.  On another, no pdf file is created.  We can see the document/job getting created in the PDF Print monitor, but after it disappears from the monitor, there is no pdf file.

What can cause this, keep if from being saved?