I just bought the Chamberlin garage door openers so that I can open and close the garage door remotely. Once I installed it and synced it to my Liftmaster garage door opener it would open the door but not close it. In fact the only way I can get it to close is to hold down the button on the wall. It was working fine before I installed it? I noticed the led is blinking 3 times if that helps. Any ideas what is causing the problem. Maybe it is not compatible with My Garage door opener? also I unplugged it and took the sensor of the door and same results.