If you are having problems with you're pen display when it is attached to your computer such as:
Not seeing anything
Odd Flickering
Weird colors
"no signal"
Then one way of identifying where the problem is try connecting your pen display to another device that provides a display signal. Here are some examples of devices you might already have:
Another computer
A gaming console like XBOX or PlayStation
A DVD player
Mirrorless cameras
If you can get a steady working image from another device, then it helps exclude the tablet itself as the source of the problem.