If it is not locking the magnet driver might have gone bad or got shorted, put it on really light pressure make sure the strike plate hits the magnet flat and pull up on the handle afterwards then you"ll know if it's locking or not. If it comes off with a pull your magnet driver went bad or your sensor is bad. If it's under warranty call stahls, if not call to see if you can order a part to replace it. Hope this helps