Hi , i have replaced a dimmer switch downstairs but its not working, i copied the old wiring, i have 2 red wires and 2 black wires, the 2 red wires were in the squigly hole and the black wires 1 black wire was in the l1 and 1 black wire was in the l2, the dimmer switch is downstairs, but in controls the light on the hall landing upstairs, there is a standard switch upstairs which also controls the said light. Can someone help me please.