I have a 2 gang dimmer switch which work both lights in the room ok (a main and a side light) The other switch has never worked properly only switching the main light on, but won’t switch off the light when dimmer is on, it just gives the full power to it. In the switch there are 3 wires, a red, a yellow with red sleeve, and a blue. Does this mean that the switch has never worked 2 lights? How do I wire the switch, so that it switches off when the dimmer is on? Any help appreciated, thanks