Multidomain issue

We recently upgraded to Wordpress 3.1.3 and upgraded our to plugin to 1.1.4.

We're having an issue when trying to create new blogs on one of our multiple domains. In our case, the primary domain is mychiroblog.com, and the second domain is myministryblog.com. When we try to add a new site to the myministryblog.com domain, we get the following error message:

"The site you were looking for, http://myministryblogcom.mychiroblog.com/, does not exist."

The sites page confirms that the blog hasn't been created.

We've recently upgraded our Wordpress installation to use multiple databases, but haven't had any other problems.

Thanks,
Dr. Pat