PowerDevil screen powersaving problems

[Snake]

Hi,
I have some problems with KDE4.2 PowerDevil screen powersaving. First one is that dimming of the display when idle for x time doesn't work. I have set it to 1 minute but nothing happens, do I have to enable something in kernel? Also changing screen brightness doesn't have any effect (keyboard keys for brightness work fine).
Second problem is that power management for screen in profiles doesn't work. I have enabled display power management but standby/suspend don't work. What is pretty weird to me is that options which I set in Display -> Power control work, but settings in profiles have no effect.