Maybe getting no printers is actually correct?

I've just used the script against some of my Citrix farm members.

Although these will have dozens of (network) printers connected for all the users, the only printer that the script actually reports is the "Microsoft Office Document Image Writer" which is created when Office is installed.

The same applies when run against co-worker's machine - only the Office printer appears.

Perhaps you need to run the command in a different context?