I don't know what you are saying. If you install the PDF driver from TMG (as above), it is listed as a printer driver in the system Devices and Printers list - "Wholly Genes PDF Writer v3". While the PDF driver is in the list, it cannot be used as a selected printer either from TMG or from any other application. The only way that it can be used is by outputting a report to Acrobat (PDF) from TMG.
Okay - you have answered that part of my query - thanks.
Now back to the topic in hand. How can I get rid of this Error 20 message. I do have Acrobat (PDF) checked in Reports/Output Tpes in Preferences.