Please check your Order Confirmation email for the stock availability message of the item. If it has a "Usually ships..." message, it will be shipped out to you at a later date within that time period. For example:

In other words, for orders that contain both "In Stock" and "Ships at a later date" items - we ship out the "In Stock" items immediately and send out a later shipment for the remaining items. 

If the item that is missing from your order is "In Stock" - please Submit a Query with your order number and the item/s that is/are missing from your order. We'll start an investigation with the Warehouse orders fulfillment team as soon as we receive your query.