Aeon Labs door sensor not triggering

I have just installed 2 Aeon door/window sensors. Both included fine (although temperature sensor did not show up yet). One of them works fine, changing the status to red when i open the door, when i close the door goes green. The other one does nothing, stays on green. I have the short blue flash on the sensor when i open/close the door, but in vera it stays green. Has anybody had that problem ?