This is the first time . I'm setting up MU site with domain

This is the first time . I'm setting up MU site with domain mapping using your plug-in.

I was on a roll to I got to the domain mapping part. I can add subdomains with no problem.

However when I go to enter in a new domain that I want mapped. I get this message "Missing or invalid site address."

I must have missed something?

Ron