Check your settings that this function is set to Auto.Iv got mine working but only switches 1 way.
If you put the head lights on then press the night&day button twice the screen will turn blue on mine.You can set it to black as well but that is in the settings.Then if i turn the head lights off the screen will go to day mode.
Update guys OK do as i said and set the sat nav to Auto for Day&Night mode.
As Dan pointed out click back your dimmer button 1 click and bingo works perfect.
This is the long button about 30mm long on your display behind the steering wheel.
:lol: Me to just been out and its a 2 second job.Let me no if yours works as well lol
O dont forget to turn your lights on and off as this operates this function.