Check if the Load (switch-leg) wire (typically black) is properly connected to RD.
Confirm a Neutral wire (typically white) is properly connected to WH. If you need assistance determining if you have a Neutral, view this video.
Confirm a 110VAC Hot wire (typically black) is properly connected to BK.
Confirm the light bulb is functioning properly.
If you are unsure with the wiring, please contact an electrician.