Safety mechanism for trouble-free operation Any of the following conditions activates the camera’s safety mechanism, locking the shutter. A LED in the viewfinder alerts you to the problem and indicates what you need to do to correct the situation. Problem Alert Conditions  Lens not attached      Film not loaded Shutter lock LED indicator flashes in finder  Film not fully advanced  Dark slide in place  Low battery power    (flashing LED)     AE, AE-L position dial lock The dial locks automatically whenever it is set to the AE or AE-L positions, to guard against accidental movement. Hold down the release button to rotate the dial and change to the Manual Mode.