ORA-12514: TNS:listener does not currently know of service requested in connect

 I am upgrading from my existing oracle 10g DB to 11g.

The DB is in the local server. I have configured my listener as:

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = /applns/oracle11g/app/oracle/db_1)
      (PROGRAM = extproc)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = N348)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
    )
  )

I dont have any issues in connecting to a already running 10g DB from 11g client.

But when I shutdown the DB in 10g and try to startup upgrade from 11g its giving an error:

ORA-12514: TNS:listener does not currently know of service requested in connect