AirPlay not working wirelessly

I'm having an unusual issue with XBMC and AirPlay.

I can only AirPlay from my desktop computer (wired) to the HTCP box (wired). My iPad and iPhones won't see XBMC as an airplay client. They can see my AppleTV (wireless), but not XBMC (wired).

Any idea why AirPlay would only work from a wired desktop and not from a wireless iPhone or iPad?