Obviously, so do I.
I think it's because in the past I've acquiesced to their demands and just vacated the room without question. Maybe word has gotten around that I'm an easy touch.
But anyway, I got a "Do not disturb" sign from the reception.
And yes, I've pushed the button on the bedside selector, but to no avail. It's probably not working, or maybe it's like the "close doors" button in the elevators - it's not actually connected to anything!