BuddyPress.org

sorry for not clarify issues.

First,
In Registration Settings, I selected “Both sites and user accounts can be registered.”
And When I sign up a new test account , and select to create a new blog with a given sub domain name.
But, there is no new blog created , the test account only become a member of the main site.

please check it from here: http://usenode.com/register/

you can test it.
Thanks.