Can't access the forum but can access configurations for it in drupal admin

The error i get is a standard 404 when using the menulink for the forum.

My installation is perhaps somewhat different from regular installs, but it is because it's a testplatform.
My drupal web root is: www.lassi.se/pendulum.se/
My phpbb web root is: www.lassi.se/pendulum.se/phpbb/
As stated in the Title, i can see all phpforum related stuff in the administration-panel and can edit all stuff. But when i put up a menu link i get a 404 due to the menu link actually leads to www.lassi.se/phpbb/ and not www.lassi.se/pendulum.se/phpbb/

What do i need to hack to get this to work properly?