I cannot change my screen brightness at all in Ubuntu. i could not do it in gutsy and i have just upgraded to 8.04 and i still can't change my screen brightness. I have tried using the function keys which shows the bar which is supposed to control the brightness, and i can move it up and down with the function keys fine but it doesn't change the screen brightness at all. I have also tried clicking lower my screen brightness when on battery power in power manager and unplugging the laptop and the bar moves down but again the brightness does not change.
It is probably something i am doing wrong, but is there a way to fix this?
Thanks in advance.