USB ports on ADC display not working

[uizin]

Hello everybody,
I am setting up a beautiful Power Mac G4 Cube. I am exploring OS 9.2.2 and everything works great. One issue I am having Is that the USB ports on the rear of the 17" cinema display connected through ADC are not working.

On the System profiler I only see USB 0 and USB 1, which are the two ports on the Mac itself.

The video card Is a 64mb GeForce2 TwinView).

Is there some setting I should check to get them working? Or am I missing something else?

Thank you for your replies!

[Protools5LEGuy]

I have a Cinema HD and the previous owner disabled the backside USB connection and the power button.

It was easy to get them back to work just by connecting it again. Mounting back the monitor was not easy, by the way.

[uizin]

Thank you for the hint!
So an hardware issue is my best bet to start troubleshooting?

[Philgood]

I have no solution for that but I'm also owning a 22" ADC Cinema Display with wonky USB ports. They seem to work only sometimes.
I opened it up but didn't found anything visually wrong with them.
The track record of having them working seems really random though I just try to dont rely on them. Happily I have 2 more Cinema Displays without that issue.