My home was built in the 1950's so it has old wiring. As far as I can tell I have no neutral wire at my switch. I purchased the light dimmer Lutron PD-6WCL which it says does not need a neutral wire to install. Installation instructions say to join the ground from wall to green on switch which is easy enough. Then it says to join the other two wires to the two on new switch but I only have one wire left in the wall. I only have 2 wires total in the wall switch. I am not sure what to do next. Thanks for any help.