Can’t get buddypress notifications in front-end; why do I get this error?

use this:

 
if ( !function_exists( 'bp_core_get_notifications_for_user' ) ) { 
    require_once '/wp-content/plugins/buddypress/bp-core/deprecated/1.9.php'; 
} 
function cg_current_user_notification_count() {
    $notifications = bp_core_get_notifications_for_user(bp_loggedin_user_id(), 'object');
    $count = !empty($notifications) ? count($notifications) : 0;

echo $count;}