Auto transmission issue

Hey,
I bought a 95 Elantra with an Auto tranny that supposedly had a blown motor, since I had a motor replacement I went ahead and bought it. So I replace it with the motor and put the tranny back on and start the car, motor runs great but my problem is now that I shift the shifter through the gears but the car is not moving.
Everything is connected the way it was and when it's in Park you can't move the car...
Put it in Reverse and reverse lights come on but the gear doesnt engage even with me giving it some gas, same in D,2,L.
Anybody have any ideas what that would cause?
Thanks

my friend has the same type of problem '95 auto wont shift out of park. he says that the gears have locked together in the tranny. so is going to do a complete tranny rebuild. can be done professionally for $350+ i believe. hope this helps