Smile [Q] omnirom for n7000 does not go to sleep

Hi ,
I installed Omnirom for Samsung n7000. However it does not go to sleep. And the screen is always on. I have set to sleep if idle time is 15 seconds or more. I have tried to set keep alive of all the apps permission to off. However, Omni does not go to sleep? How to solve it?
Thanks.