I'm not certain, but I suspect that the problem is Windows 10.
You should be able to find info about this thru the web.
The specific problem may be that W10 is nothing like as flexible with the midi connection, and the Midi Mapper. Up to XP, there was a specific (named) midi mapper, and it was directly accessible, and it was relatively easy to link things in so that Windows could see the midi devices. With W7, this became less clear, but it was still possible. My understanding is that with W10 it is more or less hidden away, and it is NOT directly accessible at all.
If you find the web site for 'Virtual Midi Synth' that will give more info about this, and I think you can download something to provide a repl Midi Mapper, or help link your system to midi. Of course, the actual VMS system may be useful as well? There will be other info about linking other systems within W10 elsewhere on the web, but you're looking for info specifically re W10, and Midi Mapper, and prob specifically USB Midi?
Geoff