Costing enabled flag trigger does not work

Usually when the costing enabled flag is set as Y at item master, the item cost would be automatically created (the record will be inserted into cst_item_cost table). Due to unknown reason, the item cost is not created after the costing enabled flag is checked for one item. I created the item cost with pending costing type for this item, and then I ran the cost update program to update the cost to frozen costing type. After the request completed, I found in item cost window, there are two types of costing for this item. One is pending type and