China post air mail says NULL on tracking status for 14 days now!! WHATS HAPPENING? My tracking number is RB859184875CN

hello ! Ive been buying a headphone from aliexpress,and the seller sent the item with air mail! My tracking number is RB859184875CN and for 14 days it says NULL on tracking status! Please can someone help me trackingnit and explaining when i will recive it??

Thanks