It could be as simple as not enough movement for sych, the switch, relays, TC shift motor or worse. If it hasn't been driven much (exercised), they do get sticky. I would almost say it is the TC shift motor, but you have to run through a thorough trouble-shoot procedure to find the problem.
Pull out your book for the fuses. The relays are between the driver's side battery and the fender of the engine bay. Check for power at all locations. Listen to what is going on when you move the switch. Do you hear clicks from the relays? Do you hear clicks from the shift motor? Does the vacuum pump start (may not have to)?
Read some of the post in this section. Search out ESOF.PDF of similar and you will get good direction on how to proceed.