BuddyPress.org

hi , i have this error : Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'bp_group_new_topic_button' not found or invalid function name in C:\wamp64\www\wp-blueprint-base\wp-includes\class-wp-hook.php on line 287
when i create a new group (displayed on the group presentation page)
what i have to do with that ?

i have installed the bp-default buddypress theme

regards
charly