Hmmm, let me just preface my comments by... it been more than 10 years since I last used this thing. Glenn may have used it a little more recently.

When I made this there were no "Universal" printer drivers, so this could have something to do with it.

The function simply looks through the INF and tries to find the model you specify in $Printertype, so while it may actually find what you provided, there is no guarantee there is actually a section in the inf that works for the printer you are setting up. In hind sight this is a major flaw of this UDF.

What is the @error after the function, and is the Port Unknown a gui displayed error or is that happening in the script too?