tnsping service_name 返回状态正常！
sqlplus  userid/passwd@service_name 出现ORA-12514错误.
前几天11g中也碰到了这个问题，今天的版本是Release 10.2.0.1.0也遭错误.
解决办法是修改listener.ora中SID_LIST_LISTENER

修改前:
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = /oracle/app/oracle/product1)
      (PROGRAM = extproc)
     )
   )
--------------------------------------------------------------------------
修改后:     
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = /oracle/app/oracle/product1)
      (PROGRAM = extproc)
     )
    (SID_DESC =
      (GLOBAL_DBNAME = DD)
      (ORACLE_HOME = /oracle/app/oracle/product/10.2.0)
      (SID_NAME = DD)
    )
    (SID_DESC =
     (GLOBAL_DBNAME = data)
     (ORACLE_HOME = /oracle/app/oracle/product/10.2.0)
     (SID_NAME = data)
     )
  )

修改后 看看状态:
bash-2.05a$ lsnrctl status

LSNRCTL for IBM/AIX RISC System/6000: Version 10.2.0.1.0 - Production on 05-MAR-2006 13:41:13

Copyright (c) 1991, 2005, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for IBM/AIX RISC System/6000: Version 10.2.0.1.0 - Production
Start Date                05-MAR-2006 13:12:43
Uptime                    0 days 0 hr. 28 min. 29 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      ON
Listener Parameter File   /oracle/app/oracle/product/10.2.0/network/admin/listener.ora
Listener Log File         /oracle/app/oracle/product/10.2.0/network/log/listener.log
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=dev_card)(PORT=1521)))
Services Summary...
Service "DD" has 1 instance(s).
  Instance "DD", status UNKNOWN, has 1 handler(s) for this service...
Service "PLSExtProc" has 1 instance(s).
  Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "data" has 1 instance(s).
  Instance "data", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully