Oracle – Cannot connect to ExtProc In Oracle 11g

We have two Oracle instances on one server (both 11g) that are using the same listener. I am having an issue with connecting to the extproc:

TNSNAMES.ORA

EXTPROC_CONNECTION_DATA.NATIONAL.SERVER.COM =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC11G))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = PLSExtProc11g)
    )
  )

LISTENER.ORA

(DESCRIPTION_LIST=
    (DESCRIPTION =
       (ADDRESS_LIST=
         (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
         (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC11G))
     )
    )
  )

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc11g)
      (ORACLE_HOME = /home/app/oracle/product/11.2.0/dbhome_1)
      (ENVS = "EXTPROC_DLLS=ANY")
      (PROGRAM = extproc)
    )

When I use TNSPING to check the connection, I get the following:

/home/app/oracle/product/11.2.0/dbhome_1/network/admin/sqlnet.ora

$tnsping EXTPROC_CONNECTION_DATA

TNS Ping Utility for Linux: Version 11.2.0.1.0 – Production on 03-NOV-2011 14:03:41

Copyright (c) 1997, 2009, Oracle. All rights reserved.

Used parameter files:

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC11G))) (CONNECT_DATA = (SERVICE_NAME = PLSExtProc11g)))
TNS-12541: TNS:no listener

I am able successfully tnsping both of the databases but not the EXTPROC_CONNECTION_DATA.