92' Seville Back Doors Not locking or unlocking
 

My 92 Seville STS the back doors will not lock from the driver or passenger side or from the back seats. But if the lock button is pressed from either back seat it will lock the front doors but not unlock the front doors. The windows roll down fine from the driver side and both rear doors. Not really sure what is causing the problems. If you need more info please let me know as I will do my best to get the information to you. Thanks in advance.