BuddyPress

In one of my WordPress BuddyPress installations http://bouw.fnv.net/
Dashboard – Design – Themes – reflects as the active theme the default site (BuddyPress) theme and NOT the real active theme. In all wpblogs/wp-admin, except of course in the root/blog – How to repair?

Header change doesnt work, only changing of the default root site header possible. Part of the same problem, I thinik

Additional information
Theme preview,
a right one

http://opdebouwplaats.fnv.net/twitter/?preview=1&template=connections-reloaded&stylesheet=connections-reloaded&TB_iframe=true

the wrong one in blog/site http://bouw.fnv.net/twitter/

http://bouw.fnv.net/?preview=1&template=connections-reloaded&stylesheet=connections-reloaded&TB_iframe=true

should be –

http://bouw.fnv.net/twitter/?preview=1&template=connections-reloaded&stylesheet=connections-reloaded&TB_iframe=true