1999 Honda Civic rear passenger side door wont lock

i had a 1999 honda civic lx, the door on the rear, passenger side wont lock, i've already tried locking it manually but still when you open it from the outside it would still get open, even if i engaged the anti-theft lock, still it would open up. another problem is about my auto locking system using the anti-theft system, it function normally on all door except on the driver side lock, meaning the other three doors would lock up ( except the door on the rear passenger side, but the locking tab inside the car would go down if the anti theft is engaged) except the driver side door. hope you can help me with my problems, thanks and more power to your website.