elipackard

I am new to this forum, ive been doing some browsing and found nothing. i have a 1991 lexus es250. the car doors will unlock but wont lock. i tested the switches they are all working, and i replaced the power lock relay aka. the theft waring relay, ive tested all the wires, ground ect. when i press lock all the doors should lock, i dont understand. any information would greatly be appreciated.