CDJ 3000 - Play/Pause & Cue Button Light

When the deck is not playing the buttons are not lit up. When I hit play, the button lights up and stays lit while playing. The cue button only lights up when it is pressed.

What is the cause of this? How can it be fixed?

I have CDJ 2000 nexus 2 and the buttons are lit up as they are supposed to be.