Getting a blank .pdf

We have an older program (Meditech Magic) where the Printer setup is pretty limited.  In the setup it asks for a Port# and we always use 515.  I setup a shared PDFCreator printer that is on a server and does autosave, but when the file is created it is blank.  If I use any other Port number then the printer reports that it is busy.  Also, I am restricted in what "driver" within the application I can use for the PDFCreator printer.  I have tried both generic & HP4, but still just get a blank page.  I can print locally from the PC to this server and that works, but does not fit in the process that we need.  Any ideas on how I can get the right print stream to the shared PDFCreator?