Steering wheel options for us Early A drivers

Is there a shiny chrome circle on the steering wheel center ? Almost looks like tinfoil.
That is the contact for the horn button.
I believe you have the horn button twisted on to far, which is contacting the center.
Try backing/unscrewing the button off a touch, so it isnt making contact with the center.
It should only make contact with the center when you push the horn.

Also: Do you have the spring installed between the horn button and steering wheel ?
Very important, it keeps the horn button off the steering wheel, and horn contact.