This is because there was a problem with the spit marks and the number on the skin. The system couldn't tell if it was "spit1" skin #4 and so on, or "spit14" skin #xxx...
Hopefully they'll release the spit 1 and spit 14 skins soon, as they re-did the way they're named (put an "_" in the naming convention) but for now I'd suggest downloading it in the arenas, if you can. It's a nice skin, worth seeing.