Cause: An ADD_SUBSCRIBER or ENQUEUE procedure with a non-NULL address field in the agent type was issued on a queue whose payload has a REF attribute. Propagation of object type payloads that have a REF attribute currently is not supported. See the solution below.
Error solution: Specify an agent with a NULL address field so that the agent can dequeue from the same queue. Or, change the object type definition to one that does not use REF attributes.
Database version: Oracle 11g Release 2 (11.2)