Diagnosis
You are entering user-specific settings for BOM maintenance.
You have entered &V1& as a default item category for document items.However, this item category is not for document items.

Procedure
Display a list of the item categories defined in your company. To dothis, look under the settings in Customizing (Bills of material)Item data -> Item categories.
For document items, you can only choose an item category which containsthe document item indicator.