I have a Sears Craftsman garage door opener model 139.18778 with a 3-button transmitter. Recently I tried to re-program an old transmitter that a friend gave me and I messed up the whole thing. I managed to find the instruction manual and reset the dipswitches and the opener now works but the problem is that I can't get a signal. To get it to work, I have to hold the transmitter up to the opener or get it to touch the antenna then it works, as soon as I move away from the receiver, nothing happens. Anyone out there have any ideas of the problem.