ORA-28582: a direct connection to this agent is not allowed
Cause: A user or a tool tried to establish a direct connection to either an external procedure agent or a Heterogeneous Services agent, for example: "SVRMGR> CONNECT SCOTT/TIGER@NETWORK_ALIAS". This type of connection is not allowed
Action: When executing the CONNECT statement, make sure your database link or network alias is not pointing to a Heterogeneous Option agent or an external procedure agent
https://support.oracle.com/
http://www.oracle.com/