No brightness control for Cinema Display

I got a new workstation and am having a problem with the very bright display. I've been digging around, trying to figure out how to adjust the display but can't figure it out. When I call up the Display panel in the System Preferences there are no control sliders for brightness or contrast and checkboxes for ambient light (only thing I can do is choose color depth.) The keyboard controls do nothing either.

The USB cord from the Cinema display is plugged into the computer. I've tried resetting the SMC. Nothing seems to work. Also tried the "Shades" utility and that also did nothing. Any ideas?

Message was edited by: Wes Rand

Message was edited by: Wes Rand

Message was edited by: Wes Rand