A380 PHX-LIM Cannot add flights

Trying to start service from Phoenix Sky Harbor to Lima, Peru. Chose an A380 because I was slot limited at PHX. For some reason, I cannot add flights using the Whale PHX-LIM. It is not a runway length issue, both airports have 11,000+ foot runways, so I am at a loss as to what else is wrong. Please help. I am in S1.