I'm trying to install a Lutron C-L Dimmer for a light switched from two locations. Unfortunately, the switch I want to replace has two black wires, two red wires and a ground wire. I can't figure out how to wire this configuration to the dimmer switch. I tried tying all three black wires together but that configuration disables the second switch to the light. Can anyone tell me how to properly hook up the dimmer in this case?