My son threw his backpack and knocked one the sensors out of the bracket located on the garage door track. I screwed it back in place, and both sensors are lit up; the sending sensor is orange(amber as the handbook states) and the receiving one is green. Both have steady bright glows. Yet, the garage door will start to close only to open again once it reaches the exact postion where the sensors are. There is absolutely nothing blocking the doorway. Any ideas?