Broken,bent,out of adjustment.spring collapsed. Could be many things. Get a can of wd40 and spray the lock and mechansim with it then wipe the dribbles/excess off the paint and open and close it a few times. It also depends on how cold it is outisde right now where you live. The mechanism/lock coul dbe froze up. This is why it needs lubed at least once a year or when you notice it not closing/locking. Againa it depends on what you find when inspecting the lock/mechanism.oh almost forgot shoot some wd40 on the key and put it in the lock and work it back and forth. It also depends on if you mean it has a electronic lock/operating system. This could be a worn out actuator. Which is activating even when it should not be.in other words it could have a short or be receiving a signal even whne it should not be.in other words an electrical problem not a mechanical problem.it could also be a drained battery in you key fob sending duplicate/double signals. Or what I call fat fingers hitting more than one button on the control.