The url we are testing this at is
www.downlinesrus.com/joomla
As we have not been able to successfully register any test name there is no particular test name that is required.
We did add the [NAME] field as a required field
as well as [UserName] and [EmailAddress] as none of these fields came with the installed version which I found to be somewhat odd.
When I first added the Title of the NAME field I received a popup which stated that SQL required the cb_ to preceed the field name, and that it had set this into the name title.
Cheers,
Roberto