While unusual, there are instances where a dimmer or switch may stop responding to pressing the on/off paddle or dim/bright bar.
In these instances, you need to power cycle the device. If it is a dimmer (DL6HD / DG6HD or DL1KD), simply lift the bottom of the dim/bright bar until either the light or LED at the bottom of the dimmer turns off. Wait 5 seconds and then push the dim/bright bar back in, the dimmer will restart.
To power cycle a switch (DG15S or DL15S), you will need to flip the circuit breaker powering the switch off for 5 seconds, and then flip back on.
If the loss of control continues or if you have any questions, please contact support at DSSupport@leviton.com.