We have a Liftmaster garage door opener, part # 41AC050-1, made in 11/08. The push button wireless door opener, model 377LM no longer works. We bought a 877LM but it would never program. The lights flashed as the instructions said it would but it never worked. We were going to send it back but we misplaced it. What model number works with the garage door opener that we own? The door openers work fine when we push th buttons inside our back door. The car remotes work well. We would like a keypad to use as well.