In my back room i have an inside light and a outside light, all 3 core wires. i have got a 1 way switch with red,black and earth wire to it and a centre light connected to it but it doesn't work, then there is a 3 core wire comming down the wall and was connected to another switch then from this switch another 3 core wire which goes to an outside light. Now when the 3 core wire comming down is connected to the outside wire with red to red, black to black and so on, the inside light switch works the outside light. How can i make the inside light work and keep the outside light working. Please could you tell me where the cores are wired to eg com, L1 and L1?