Problems in my Samsung Galaxy S4's Smart Screen Feature

[Alextodd1]

Smart Screen feature was the only reason why i bought S4 in first place. In the beginning my Smart Stay, Pause, Rotation etc were working perfectly, however it used to give me problems in Low light but at day time it worked like a charm. But from the last 2 days it is giving a delay in response or is not responding at all even in day light.