SAP Message 29254 - Standard products in plants & and & are different

Diagnosis
You want to allocate the BOM of a configured material in plant &V1& toplant &V2&.
The material was configured with reference to a different configurablematerial in plant &V2&. Once you have allocated a material to aconfigurable material, you can no longer change the allocation.
For this reason, you cannot create the allocation to the plant.