Ive purchased an aftermarket brakelight and Im stuck on how to wire it. The stock tailight on my sl350 had 3 wires going out to the switches, battery and ignition switch. On This new one it only had a red wire and a black wire so i sent the black to negative battery side and the red i split out to the ignition switch and brake switches. It comes on fine with the ignition switch but no change when the brake switches are engaged. Any ideas?