Step one is to have someone hit the button when you have the jack compartment (drivers side, rear) open. You should hear slight clicking in there.
If you do, then the next thing to check is the shift motor. There are many threads here about how to rebuild/clean it. That is a very common issue. I don't remember seeing many problems that weren't caused by the shift motor or the wires going to it (mine were missing most of the insulation so between the motor needing a rebuild and shorted wires, mine wouldn't work)
~Mark