Many of these devices use a code that changes each time the door is opened and closed. This feature is used to keep potential bad people from learning your operational code and entering your garage. You may have a communication problem whereby the Garage Opener needs to be reset. You may try to change the settings. If you have dip switches on the main unit in the garage, change the dip switches to another setting and write down the numbers in the order that you have the set them, Then go to the remotes, hand held and hardware placed on the outside door, and change the settings on these devices to MATCH up with the inside unit. This is a good time to REPLACE the batteries also.