Fatal error, buddpress, studio theme....

Hi,

I'm hosted at Psek on an WP install setup by wp.mu.

Yesterday I upgraded to WP 3.0 and uploaded the studio theme.

I also asked Psek to change the sites top level domain from http://taiwanblogs.org/ to culturemedia.asia.
This appears to have caused the issues. Perhaps something to do with domain mapping. I'm unsure.

Fatal error: Call to undefined function bp_get_displayed_user_username() in /home/taiwanbl/public_html/wp-content/themes/studio/library/functions/bp-functions.php on line 18

Psek have assisted with backups & restores (thanks!) but no luck so far
Any advice would be much appreciated.
Thanks,

Jeff