I have a 4-wire system coming from the house to the garage. There is 2 black, one white , and one green. There is a panel in the garage with a three wire system, one black, one white, and one ground (12/2). How do I connect this up? I know normally the black goes to black, white on white, and ground to ground. I’ve tried that and get no power for the garage electricity. What do I do with the other hot black wire? Both black wires coming from the house wires are hot!