Air horn issue

[yoda]

So for 10 years or so I have had a Bad Boy air horn on my 07 1600. Worked fine until last week when out of the blue it quit. I could hear the relay clicking so I checked for voltage to the horn. Nothing, so I went to the relay to check voltage coming out of the terminal. Nothing. Power coming to the relay was good, so I replaced the relay. Now power comes out of the relay, all the way to the connector for the positive terminal on the horn. Still doesn't work. I checked the ground connection, and cleaned that up (wire from the - horn terminal to the mounting bolt for the horn to the frame), and since I had the old horn off and it rattled a bit when I shook it, I got a new one. Mounted it up, plugged everything in, and it still doesn't work. I checked the voltage with a meter hooked to the power connector for the horn terminal, and the ground terminal. Everything is good. Nothing on the power side on the meter, until I hit the horn button with the key switch on, then it goes to 12v and drops when the button is released. The horn works with direct connections to the battery, so I have ruled out a defective horn.
So to summarize, what am I missing, if I have voltage coming to the positive terminal on the horn, and a good ground to the negative? I assume the switch is working due to only sending power to the horn when button is depressed. All the wiring continuity checks out, the power is there, the ground is there, but it doesn't even give a wimper. (Although I am now deaf in my left ear after testing directly to the battery...)