Typically if you have received your shipment and something is missing  it is on back order.

Items that are out of stock at the time your order is placed will be put on backorder and your credit card will not be charged for that item until it ships, in addition if your order requires more than one shipment due to a backorder you will not be charged shipping for the additional shipments. If an item is listed as out of stock and you would to like purchase it, we suggest you do so, backordered items normally ship in 2-4 weeks and are shipped on a first come first served basis via either Priority Mail or FedEx Ground. You may cancel a backorder order at any time before it ships. Please click here for other important Terms & Conditions, including our return policy. 

If an item on your invoice is showing in the shipped column and you did not receive it, please contact customer service immediately.