Pull each horn's terminals and being careful NOT to short either to ground or each other, attach a Volt/Ohm meter (set to Volts in the 20V Range [or better]), then position said meter that you can view it from the driver's position and (Important part here...) with the car NOT RUNNING, try to toot the horn.
If the meter deflects in the proper direction (if not, reverse the leads), then the horn itself is kaputz.
If nothing happens, recheck your connections and try again.
If STILL nothing happens, then you get to trace the wiring for either a burnt lead or you're looking at another fuse situation...like checking the fuse block for the horn's lead, switch (the button/pad on the steering wheel) or the leads to and from the pad itself.
Happy tracing.
