Default Carbon Rom 4.4.4 call screen problem

I am having problem with the call screen. I call someone and while I am talking the screen becomes off as usual while the phone near my ear but when I take phone away from my ear, the screen still stay off state and it does not change to on altough I press the power and all of the other buttons. But it does not happen all the time. Does/Did anyone have this problem? And who knows the solution?