Item instances are not automatically created

 Hi, there          I created an serialized item which is OAT tracked.  I created a purchase order with this item and apporved it. The item is then received into inventory against the purchase order. After the transaction in inventory, the item instance is not automatically created in OAT module.

          The same thing happens when I perform the miscellaneous receipt.  I don't know the cause. My key setup listed as follows:

1. Creat Item

 in the Inventory tab, the item must be an inventory item, stockable and transactable

- in the Service tab, Install Base tracking must be enabled and Asset Tracking must be Create Depreciable Inventory Asset.