SAP Message 29371 - Item category & does not allow you to enter a class

Diagnosis You are creating or changing a BOM item and have entered item categoryV1 and data for a class. The item category is used to link the item to a specific SAP object.Item category &V1& does not allow you to enter an item with class data. Procedure Please correct the item category or delete the class data. You can cancel entry of this item by choosing the system-wideCancel button.