I need help with correct wiring diagram for a X7299-W switch combination receptacle. the old device was a single switch controlling the bathroom ceiling light. I live in an older home, there is only 1 cable line containing 2 wires that go into the wallbox. The switch combo( X7299-W) I purchased has two black switch lead wires coming from it, I'm not sure where to connect them And I haven't been able to find a wiring diagram that fits my situation. I would appreciate any advice.