SAP Message VV502 - Material & is locked (availability check not possible)

Diagnosis
Material &V1& (plant &V2&) which you are processing is blocked by userV3. the system has attempted several times without success to block
the material you are using.

System Response
To not hinder your work, the system stops its attempts of blocking anddoes not carry out an availiability check.

Procedure
The transaction you are processing is not confirmed. Youshould therefore carry out another availability check.