The slider is for length of time the light stays on and the knob is for the amount of sensitivity. But first, step number one is to make sure power to the light is turned on! (Also note - some motion ...

I thought some of these would hold up better ...

Movement-based lighting suggests activity inside, which helps deter opportunists. Automatic light on stairs, landings and entrances reduces falls and avoids leaving circuits on. Hands-free access ...