Is it possible there has been either a door replacement or fob replacement so that the key portion of the fob no longer is a correct match to the lock in the door. While the fob could have been reprogrammed to electronically operate the door locks, no reprogramming will help if the key isn't cut to match the cylinder in the lock.
If the key still works inserted into the steering column to start the car, then the problem might be in a mismatched door lock cylinder.
Have you tried some lubrication of the lock cylinder? powdered graphite or WD-40?
If the key still works inserted into the steering column to start the car, then the problem might be in a mismatched door lock cylinder.
Have you tried some lubrication of the lock cylinder? powdered graphite or WD-40?