BOM sub item missing in Delivery

Hi All,

In Sales order, I have a BOM item with one header item and three sub items.

The header item has an item category - ZN01 and Item Line number - 10

The Three sub items has an item category - ZN02 and Item line number - 11,12,13 respectively.

I created a delivery document with reference to this order. All the items are copied into delivery except one sub item (line item number -13).

Kindly suggest why this would have happened.

In Sales order, BOM has a structure like header item and sub items, but when they are copied to delivery document, this structure is not maintained. Is it possible to maintain the same structure like header item and sub items in delivery document also ?

Thanks in advance,

Manoj