BuddyPress.org

When I visit the root Buddypress subdomain register url:

http://buddypress.domain.org/wp-login.php?action=register

it sends me to the registration page, as expected. But when I visit the same url on a different subdomain, e.g.:

http://myblog.domain.org/wp-login.php?action=register

it sends me to the WP login screen for that subdomain. That screen shows a “register” link under the login form, but clicking the register link brings me back to the same URL (http://myblog.domain.org/wp-login.php?action=register), i.e. does nothing.

Is there any way to fix this?