Index: bp-blogs/bp-blogs-functions.php
===================================================================
--- bp-blogs/bp-blogs-functions.php     (revision 5250)
+++ bp-blogs/bp-blogs-functions.php     (working copy)
@@ -299,10 +299,12 @@
 function bp_blogs_add_user_to_blog( $user_id, $role = false, $blog_id = 0 ) {
        global $wpdb;

-       if ( empty( $blog_id ) && isset( $wpdb->blogid ) )
-               $blog_id = $wpdb->blogid;
-       else
-               $blog_id = bp_get_root_blog_id();
+       if ( empty( $blog_id ) ) {
+               if ( isset( $wpdb->blogid ) )
+                       $blog_id = $wpdb->blogid;
+               else
+                       $blog_id = bp_get_root_blog_id();
+       }

        if ( empty( $role ) ) {
                $key = $wpdb->get_blog_prefix( $blog_id ). 'capabilities';