monitor power off time isn't saved

In System Settings monitor power off time unter Display/Power Saving couldn't be saved. And it seems that the standard 30 minutes always overwrite laptop-mode settings.
If I change this settings and click apply or ok, my monitor resolution is wrong after restart because "Display Size, Orientation and Positioning" shows a wrong resolution (1024x768 instead of my 1366x768) which is saved after only changing of monitor power off time. The only solution is to remove the file displayrc or edit it on my own but always if I change monitor suspend it gots reset.