For printer centric forms, the KnowledgeBase article will address watermarks on the output pages.
Are you certain the printers are properly activated and that the activation codes are current? Printer updates or physical changes(parts changed) can change the magic number that determines the activation code.
Are you certain all the printer codes are listed upon the PC that saves/sends the form to said printer(s)? If one is not listed, it will watermark.
If you have a current maintenance contract you may prefer to open a support ticket to expedite efforts:
http://planetpress.objectiflune.com/en/resources/support