I assume that the light doesn't go green, the reader doesn't beep and the screen is switched off? That sounds like a good clue that the reader may not be working?
Correct - but the readers are covered in great plastic bags as though to protect them from the rain - so you can't actually see the display.
Regulars 'in the know' have to go all the way round to the upper-foyer to do a proper 'touch out.' Most, especially tourists, don't.