I'm certainly no expert at troubleshooting these devices. But, I do have some info and suggestions that may help.
Firstly, FingerWorks is no longer in operation. Do not expect any support from the company. They are closed, indefinitely.
Next, I suggest that you try the device on at least one other computer. There have been times where users have found trouble on one machine but not on another. Often it is unexplained at first, but this helps to narrow things down a bit.
Also, on the same machine, try using different USB ports/hubs. If you are using an extension USB hub right now, temporarily remove that from the loop. The FingerWorks products all take a certain amount of current from the USB port, and sometimes the hubs are not capable of supplying adequate current. This can result in a device that works sometimes, and sometimes not... simply by virtue of the fact that the current supplied is marginally adequate.
So, hopefully you'll get some results.