SAP Message AG602 - Material & is locked (availability check not possible)

Diagnosis
The material that you are processing, material &V1& (plant &V2&), hasbeen locked by user &V3&. The system has unsuccessfully attempted tolock the material that you are using.

System Response
To avoid further delaying your work, the system will terminate itsattempts to lock the material and will not execute anavailability check.

Procedure
Note that the operation you are processing has not been confirmed.Therefore, you should execute an availability check again.