Brightness not working on G4 (running 8.04)

[njimko]

Hello. I can't change the brightness of my computer when running Hardy Heron. I've tried changing the brightness using the dedicated keyboard keys; it displays a dialog but nothing happens. I've also used the brightness applet to change the display, but nothing happens. It currently is as dim as it can be while backlit and would like for it to change. Is this a problem with video card? What can I do to get it running?

Thanks