I have a ZMNHDD1 which seems to be wired correctly as i can turn on and turn off the lights using the switch. Dimming down works, but dimming up doesn't, dimmer up using domoticz (setting the slider to e.g. 80%) also works
Pressing up should turn the light on, or when on to maximum (holding it should dim up)
Pressing down should turn the lights off, or dimming it should dim down
You could try setting it to 'single push button' for test. It wasn't mentioned that there was a 2 way switch connected so I asumed a normal simple push button.