new trans motor wont turn

hi i have a 2000 chrysler neon auto and the trans blew apart on it so i took the one out of our parts car which has a good trans but when i get it bolted up the motor wont turn over by hand to bolt up the torque converter, ive pulled it all apart 3 or 4 times and cant see anything binding up so im not sure what is wrong if you got any ideas id love to hear them, and also once i loosen the trans off the motor will turn by hand then

Sounds like the torque converter is not properly seated in the pump.