1988 Gt Reverse Glow Gauges

Hey guys,
I started installing my reverse glow gauges on my 88 GT and I've run into a problem. The instructions say to splice the black wire of the inverter to the black wire of the headlight switch. But as you can see through my pictures, there are 2 black wires. I tried them both individually and also both of them. Nothing. The new gauges aren't getting any power to them. I need some help!

Turns out the instruction manual told me to splice the red wire to the wrong wire from the headlight switch. I checked the ground wire and I wasnt splicing to both ends that I cut. Thanks for the help.