Protege5_TO

Hi Guys.

Ok.. I had transistor horns found here:
http://www.koizer.com.tw/transistor.htm for months. Last weekend i finally got the time to install them. So, the horns were installed under the hood and the electronic/transistor module was on my left kick panel. I got a small problem though. The module has a TRIGGER wire. The horns will make sound when this TRIGGER wire is shorted to ground. Now our Protege5 OEM horn has one (black) wire and the horn is mounted straight to ground.
So i thought by hooking up the TRIGGER wire from the electronic module to this black wire i would be able to use the switch on the steering wheel. But i was wrong - as soon as i hooked this TRIGGER wire to the black wire off the OEM horn my transistor horns started to blast. Tried to unhook the OEM horn and hooking this TRIGGER to this black wire ... same thing happaned.

So right now i m using a separate switch to activate my transistor horns.

Do you guys have any idea why this is happening?
Anyone has any idea where or what wires coing out from the horn switch on the steering wheel? Did not get the chance to take it apart. I don't like to use two switches for horns.

Basically i want to replace my OEM horn with this transistor horns but i want to use the switch on the steering wheel.

Any suggestions/thoughts?

Thanks.