Why don't you go through these garage door questions and answers to solve issues? Very helpful
Garage doors do this when there is some kind of obstruction in its path. Remove the dirt or obstruction and check the photoelectric eyes to see if they are aligned properly. When it does not work well after doing both, our professional repairers can help you with the issue.
Check the door sensors. There are times that they may be located too high that they don't transmit the right signals to the door. If this is the case, pull it down until it is in its right position.
To perform the photo eye test, you should push the transmitter of your door to close it. While it is closing, you should wave a long object in front of the door’s photo eye to break the beam. The door should reverse automatically.
The photoelectric or photocell system is a component of most modern automatic or electric garage door openers. It is added to ensure that the door does not cause accidents especially on children and pets. It stops or reverses the movement of a garage door when an object is detected on the door path.