When users create a site, even if domain is mapped, it takes you to the domain of the root installat

The title explains this one…

When users create a site, even if domain is mapped to their domain, it takes you to the domain of the root installation!?

Under my domain mapping options I have selected “mapped domain” for the administration. What I can’t understand is why when I am in the administration area, why doesn’t the url stay at the mapped domain for creation of the new site?

Perhaps I need Multiple Networks to make it resolve.

What are your thoughts?