I purchased a Hampton Bay Transitional Collection Exterior Motion Sensor Wall Lantern Light #561456. I can set this with either the motion sensor or dusk to dawn setting.
The motion seems to work fine but when I set it for dusk to dawn with the light comes on it just flashes, not a steady light like when the motion sensor makes it come on.
I've replaced the wall switch which sends power to the light from inside the house but it makes no difference. Why does the dusk to dawn do this? Thanks

Photocells will turn the light on and off when wired backwards.

Check to be sure the live is feeding the input to the photocell, and that the load wire off the PC connects to the light socket.