New OMP wheel - no horn

Evening, wondering if any of you can help ( i will update tomorrow with pictures )

i've recently changed my standard wheel for an OMP wheel and boss, everythings fine, including the air bag light but for the life of me i can not get the horn to work, theres one black cable which im guessing is the live, the horn sent from OMP has 2 attachments, one for the live, which i connected and the other is im assuming for a ground

no matter what i do i can not get it to work, not sure if ive busted it trying to swap cables over etc. can any one help its driving me insane?