Thanks John, but I think I am already doing that.
I now see the answer to my question: the file is being created, but the software is automatically storing it in C:\Windows, not in the working folder. Thus the stitched image is not placed in the folder with the individual images, nor at the location of the pto file. This is rather unexpected. There does not appear to be any setting in PREFERENCES or in the output dialog to change this, so I guess it's fixed. It is not a problem, as long as one knows where the file is placed. It might be nice to mention this in the help files... or maybe there is some peculiarity with my machine?
Software seems great, and well done to the developers.
thank you
Dirk