Garage Door Opener Lock and Light buttons don't function properly
I have a Craftsman 1/2HP 139.53627SRT garage door opener and neither my 'light' button or my 'lock' buttons work properly. The 'light' button does nothing, and the 'lock' button just opens and closes the garage door like the big main button does.
Everything else works fine, safety sensors, lights come on with door opening and go off after 4 minutes, etc...Any clues???
Thanks in advance!