[Vili]

Just to make sure, you don’t actually use “require_once(‘path/to/wp-blog-header.php’);”, but rather have the “path/to/” bit modified to correspond with the correct folder path to your WordPress installation, right?

As far as I can see (and I am no real coder, either), somehow your current setup still fails to connect to WordPress, and therefore the WP functions, including get_header, are unavailable to bbPress.