Message Oracle ORA-28560 - error in configuration of agent process

ERRORerror in configuration of agent process
CAUSEAn ORACLE server invoked a function not supported by the connected agent (Heterogeneous Services or external procedures). The most probable cause is incorrect Net8 setup, resulting in use of the wrong agent executable.
ACTIONCheck Net8 administration in the following ways: -- When using TNSNAMES.ORA or an Oracle Names server, make sure that the connection from the ORACLE server uses the correct SID. -- Check LISTENER.ORA on the agents host machine to assure that this SID refers to the correct agent executable in its (PROGRAM=...) clause.