Not accepting AD domain

Not accepting AD domain

I'm trying to set this up for an evaluation but the it doesn't seem to accept my domain. I've entered the full name of the domain and it asks me to use the short name. It even tells me the short name to use but when i put that short name in it says it is an invalid domain name. I cant find anything in the help to get this sorted. Any ideas?

-Mahoney
                New to ADManager Plus?

                  New to ADSelfService Plus?