Diagnosis
One of the following situations triggered this message:
You want to create the item of equipment you entered as a variant of anexisting BOM (-> variant BOM).
This is only possible for equipments for which no BOM has beencreated yet.
However, a BOM already exists for the equipment in this plant and forthis usage.
You want to allocate an equipment BOM to an additional plant.
However, a BOM already exists for the equipment in the selected plant.

Procedure
Check your entries for the equipment, plant, and BOM usage.