I have replaced a pair of old 2 way switches with new ones. There are only 3 wires going into each switch. One each thin black and red and one thicker red. I can only switch on and off from one switch at a time. I have copied the original switch connections although the layout of the new sitch is different to the old. (Old switch 3 connections vertically in line, new switch one conn at the top and two below side by side). I'm assuming the common connection is correct and have tried switching the L1 and L2 connections on one switch but this has no effect. Any advice would be appreciated thanks. Phil