Multi Domain

Hi

Multisite
WPMUDEV Multi-Domains plugin installed
Wildcards have been set up with domain provider

I have a site set up for domain.com
I can set up sites for suddomain.domain.com
I have added domain2.com

I can only seem to add new sites if I use a subdomain.domain2.com?
I'd like to be able to create a site domain2.com

Any help appreciated. It may be that I have the wrong plugin?

Thanks

Mark