Diagnosis
A lock requested by calling an ENQUEUE function module cannot be set upbecause another SAP transaction is using the lock in question.

System Response
The ENQUEUE function module triggers an appropriate exception. If thisexception was not intercepted by the application program, this leadsautomatically to the active SAP transaction being cancelled.

Procedure
Look in the lock table to establish which user or transaction is usingthe requested lock (Tools -> Administration -> Monitor -> Lockentries). You may need to contact the user in question.