Power management broken?

Currently i'm ruing Ubuntu Trusty + XFCE at a Dell Chromebokk with Crouton. Everything "at lest after a couple hours trying" works as it should and i'm happy with how smooth it is.
But......Power management seems to be broken some how and it has no effect what so ever.
If i leave the chromebook alone the brightness goes down to about 60% after 40 sec, and 10 sec later the screen goes black. The thing is, i've set almost all of the power management setting to about 10 min or so except the screen saver, that one is set to 3 min.

Also i noticed that sleep/suspend when lid is closed doesn't work. Thoose options are not even in the options. I only have Nothing or Screen lock

Sorry for my lack of English and my poor knowledge when it comes to Linux