I have an Hyundai coupe 2.7 2003 model.When I lock my car at night the central locking activates. When i push the central locking button in the morning I can hear it unlock, but the door stays locked. Both driver and passenger do the same. I open with the key and the alarm goes off. I deactivate the alarm with the button and I can open the door and start the car. For the rest of the day the central locking is OK. Why only in the morning?