I can help on this subject (I think)!
I had the most trouble setting up this device. Unknown device no matter what I tried and I got way into troubleshooting probably 4 hrs total. Then I surmized teh only thing that could be wrong was power requirements. I plugged a powered USB hub into my PC port and faster than you can say V-A-12-A it was installed. Try a powered hub if your having any trouble with that device!
CHill
I was about to toss my VA12(not sure why I hadn't yet) when I stumbled on to this old post.
My VA12a and USB mouse/keyboard both started to come up as unrecognized at the same time.
I tested my mouse keyboard on another Windows PC and got the same error so I pitched them.
I wish I had seen this prior maybe they would have worked on a powered hub too.
My VA12A now has a new life.