This is an obvious sign that beam of your photoelectric reversal system is out of alignment. Simply reposition one of the two units. If you have a wall control panel (and not a door bell), you will notice a flashing indicator light. By repositioning one of the two units, this light will stop flashing. Also, it could happen that, based on the orientation of your garage door compared to the sun, this could affect the correct operation of the photoelectric system. For a short period of time, when the sun’s rays hit the receptor unit of the photoelectric system, the system will be affected so that it reacts like an object is passing in the beam. In this case, your door will not close. The solution: reverse the two units so that the receptor isn’t in the sun, or install a shield to stop the sun from interfering with the operation of the beam. Read more about the maintenance to perform on your door opener.