Re: Adding subnav-items: bp_core_add_subnav_item()
Put this line :
$events_link = $bp->root_domain . '/' . $bp->events->slug . '/';
above your code:
bp_core_add_subnav_item( $bp->events->slug, 'all-events', __('All Events', 'bp-events'), $events_link, 'events_screen_all_events', false, bp_is_home() );
You will need the adjust the path for that variable as I don’t know exactly where your all-events.php is needed.
P.s. “bp_core_add_subnav_item” will be depreciated in BP1.1, but it has a better similar alternative that allows item positioning.