I have read over all the threads here and the internet. I have an iMac (black back) that my 27" Cinema display is connected to. USB and Displayport are both connected. Everything appears just fine. However, I cannot adjust the brightness on the Cinema display. I have tried everything. I even hooked it up to my Macbook Pro early 2011 model. Still the same issue. There is no brightness slider. The slider only appears for the native display only. Never the Cinema display. What am I missing?
Running Lion on both machines.