Printing file using that command still prints the empty file. I've also tried to follow your instructions about reg keys but nothing has changed - it still says it's unable to convert document.
I've taken a look at this 
but I didn't manage to make that work with PDFCreator: the first solution on that post tells me a print job has been added but nothing is printed, then if I try again it can't find the printer (I saw PDFCreator printer is on port pdfcmon); the second solution breaks the software and I have to reinstall it to get it back to work.