dek8tur

Earlier this week, I noticed that when I pressed the button to activate the alarm and lock all of the doors that my rear passenger side door was not locking. There was no beep when I pressed the button and all of the doors except that one would lock. However, other times through out the week the car will lock all of its doors and beep. I am not sure what is going on but I am wondering if someone can give me some guidance on what to do.