horn doesn't work

[gstam4]

in addition to other problems with my 2001 gz250 w/ 23k miles, which i bought a couple months ago, i discovered a while back the horn doesn't work. i took it to the shop i bought it from, and they tested it by hooking up a working horn to my wiring; that horn also didn't work. the fuses seem to be fine (since the relevant lights are working). anyone know what else it could be? do i need to re-wire or something?

thanks!