ORA-28546: connection initialization failed, probable Net8 admin error
 *Cause:   A failure occurred during initialization of a network connection
           from the Oracle server to a second process:  The connection
           was completed but a disconnect occurred while trying to
           perform protocol-specific initialization, usually due to
           use of different network protocols by opposite sides
           of the connection.  This usually is caused by incorrect
           Net8 administrative setup for database links or external
           procedure calls.   The most frequent specific causes are:
           --  Database link setup for an Oracle-to-Oracle connection
               instead connects to a Heterogeneous Services agent
               or an external procedure agent.
           --  Database link setup for a Heterogeneous Services connection
               instead connects directly to an Oracle server.
           --  The extproc_connection_data definition in tnsnames.ora
               connects to an Oracle instance instead of an external
               procedure agent.
           --  Connect data for a Heterogeneous Services database link,
               usually defined in tnsnames.ora, does not specify (HS=).
           --  Connect data for an Oracle-to-Oracle database link,
               usually defined in tnsnames.ora, specifies (HS=).
 *Action:  Check 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
               service name or SID.
           --  Check LISTENER.ORA on the connection end point's host machine
               to assure that this service name or SID connects to the
               correct program.
           --  Confirm in TNSNAMES.ORA or the equivalent service definition
               that service 'extproc_connection_data' does NOT contain
               (HS=), or that the service definition used by a
               Heterogeneous Services database link DOES contain (HS=).

(CONNECT_DATA =
(SERVICE_NAME = orcl.example.com)
)

    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )