Diagnosis
You have tried to select a default item category as a possible itemcategory for the chosen combination of material item category group,item usage and higher-level item.

System Response
The system does not accept this selection as this item category is theonly item category which has been assigned to the given combination ofkey fields.

Procedure
You must assign an additional item category to the given key fields.You can then mark this new item category as a default. As a result, thesystem automatically carries out the change to the default ID which itpreviously rejected.