Return history Load Failed with invalid item

We loaded 40 items' return history into biio return table. Among these 40 items, one item is not in msc_system_item table, not in t_ep_item table but all the other items are in t_ep_item table. We ran workflow that to import the item from biio return table to sales_data table and found all the items went to biio_return_err table with the error [ODPM-00075: Invalid Member LEVEL1-Item]. If we only loaded 39 items that are in t_ep_item (deleted the item that is not msc_system_items and t_ep_item table from biio return table), the import succeeded. May I know why?