SAP Message AA180 - Asset class & does not exist for main asset number

Diagnosis
You want to create an asset sub-number. The existing main asset numberhas been created in class &V1&.
Asset class &V1& does not exist.

System Response
Processing termination.

Procedure
The system has determined inconsistency between the asset master recordand the asset class. There must be an asset class for the existingassets.
Contact your Systems Specialist.