If I remember correctly you should be able to lock the door with the knob and hold the door button in while closing the door and it should stay locked?
Never had to hold the button in. Sometimes you just have to get a light and your face in there to see whats going on. Sometimes if the rod going from handle to latch is carrying tension or pressure it wont allow the lock to work. Packing the latch with lithium grease creating more resistance. Sloppy latch. Sloppy clips. Tossing stuff out as I think about it.
