access denied

after starting VirtualHere and trying to connect to a Samsung SCX-5x12 device I go an error:
"The VirtualHere Drivers could not be loaded. Try rebooting..."
The log says:
17:45:44 INFO :Drivers are up-to-date
17:45:44 INFO :CreateFile failed
17:45:44 ERROR :Hub failed to open error, zugriff verweigert (0x00000005)

The host is a QNAP TS-870 pro,
VirtualHere 1.8.1, unlimited devices.

Going into Details: the device is recognized correctly.

Trying to start debug mode: same error occured

Hope you can help me.