If you can access the connection, it would be easy to test if the switch is the problem or something else. Either a multimeter or just a jumper wire will show if current is passing the switch. You say the solenoid isn't getting power, is it powered directly from the horn button or through a relay? Often the horn button only triggers a relay to pass on the greater current needed by the solenoid (air horn) or the electric horns themselves.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI