Servers seem to be locked out for a few days. And then it rotates. I'm sure some are worse than others. But I wanted to create a new character on Cactuar, and I couldn't for about 4-5 days.

So wait, and try every day. Eventually the server lockout should be lifted.

Odd that we have rolling lockouts, but there aren't a lot of people in the starting levels except 50's grinding ATMA.