Created PDF/A-1b files not valid


we're currently trying to setup PDF Creator 1.2.3 on our Windows 7 machines to create PDF/A-1b complaint documents out of Postscript files. We do that by executing PDF Creator through command line with:

PDFCreator.exe /IF"C:/TEMP/" /OF"C:/TEMP/pdfa.pdf" /OutputSubFormat"PDF/A-1b"

The specified PDF file will be created. However, if I validate the file using several online validation sites like:


They report that the file does not meet the PDF/A-1b standard. The Postscript input file above was created in advance via print-to-file through a postscript printer in MS Word with default template and one word "test" in it.

I assumed above command line creates a valid PDF/A-1b file under all conditions. Is there something that I have missed or what is needed to create a valid PDF/A file?