Thinks that domain already exists on serve - doesn't

I'm attempting to add a domain to CWP, however I'm getting the error (with example of domain name):

Domain subdomain.domain.com already exists on the server!

It does not exist, and isn't in vhosts and isn't in the database or anything either.

Any thoughts? Adding any other domain does work.

Update: This appears to only happen on long strings, which is why I saw it when I had a (not short) domain and a subdomain on it. Although, this same domain has a longer subdomain that did work with it.

Any ideas?

Not sure, but normally you cannot add subdomains as domains.

Normally you need to add the domain first and then through the user account add the subdomain.

Again, not sure, but worth a try.

i can add subdomain in the domain area that's for sure.

just maybe something to look at when you make a new account it has a domain name added to that account, check out user accounts and make sure its not in their as a domain name.

I also discovered you cant use capital letters as well