STI 4 spoiler brake light problem
 

I replaced the low level spoiler with an STi4 spoiler with brake light, now my low level didn't have a brake light in it. I ran the wiring from the brake light on the passenger side light cluster to the spoiler.

Now with out the headlights on the spoiler light comes on with the brakes, but twith the headlights on the spoiler doesn't light up.


Any help is much appreciated.
Simon