i have a hallway and i've got two light drops one at each end of the hallway. i want them both to switch on together from either end of the hallway. i have put a 1gang 2way wall switch at one end of the hall and a 2 way pull switch at the other end. all i can get is they both come on together but they won't switch off. i have linked them together with twin and earth and i have run twin and earth for the switch wire. i have linked the two switches together with 3 core and earth.