Comment 1 for bug 484715

I can confirm this. It seems like there is no access to the display brightness information due to a lack of suitable driver. I believe it is a hardware specific problem as there is no such problem on my girlfriend's laptop (as I can remember right now). On my laptop there is also an other instance of the same problem: the panel applet named 'Power Manager Brightness Applet 2.28.1' appears with a red prohibitive sign and when I mouse over it, it says 'cannot get laptop panel brightness'.