We receive calls about this constantly. There are a few issues that can cause the lock to not function properly. During extreme heat or extreme cold, wooden doors can expand and contract causing the lock to no longer properly fit into the door frame. This can happen when I lock is installed during the height of summer or winter, once the temperature changes the door can shift causing the issue. In most cases a lock will continue to function properly, however it is recommended that you have a professional adjust your lock if you are not able to constantly arm it.