Issue with horn

My horn stopped working one day. On that day it was blowing but sound kept decreasing and stopped. So I bought a new horn. Installed it nothing still. So I checked the horn button I have installed due to aftermarket steering wheel. It's working according to my test light. I have it hooked to the power wire then to the wire going to the horn. When I use my test light and push the button it flashes when hooked to the horn connectors under the hood. I hooked the horn straight to battery and it blows. I also grounded the case but horn still did not blow. I disconnected the bulkhead connector and applied battery voltage but horn still did not blow....Horn does work hook straight to battery...Any suggestions? Inspection time soon come need everything working...lol