Membership: redirect to registration page does not work

The Redirection to Registration page does not work...

I created a new page "Mitglied werden", filled it with some Text-Content and - of course - the [subscriptionform] shortcode.

When I visit the Page via Navigation - it does work as expected.
But: if i click on /register the old Registration Page shows up. And - even worse - does let the user get an account without selecting an subscription! E-Mail with activation-key is sent and User can log in...

PS: I'm using Buddypress + BP-Social + Membership

If you want to have a look:
http://lebensschlau.de
(Registration page) http://lebensschlau.de/mitglied-werden/
(Standard Registration, no redirect): http://lebensschlau.de/register

Thanks in advance,
Rainer.