SAP Message UCFE886 - Item &2 does not have a breakdown by &1

Diagnosis
Item &V2& has no breakdown by &V1&. However, the value for &V1& isdefined in the header of the data entry layout and is not empty.

System Response
No new row can be inserted.

Procedure
Change the value for &V1& in the header of the data entry layout, orchoose a different item.