请教高手tnsnames.ora和listener.ora配置问题

我在本机创建了两个数据库实例：appdb和rman。
listener.ora的配置内容为：
# listener.ora Network Configuration File: D:\oracle\product\10.2.0\db_1\network\admin\listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = D:\oracle\product\10.2.0\db_1)
      (PROGRAM = extproc)
    )
  )
  
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.101)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
    )
  )
tnsnames.ora的配置内容为：
# tnsnames.ora Network Configuration File: D:\oracle\product\10.2.0\db_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

RMAN =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.101)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = rman)
    )
  )
APPDB=
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.101)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = APPDB)
    )
  )
出现了一个令我很疑惑的问题，恳请大侠给予指点，现象如下：
1)SQL>conn sys/sysadmin@APPDB as sysdba 这条命令可以成功连接到APPDB实例；
2)SQL>conn sys/sysadmin@RMAN as sysdba 这条命令无法连接到RMAN实例，提示：ORA-12154: TNS:could not resolve the connect identifier specified；
3)set oracle_sid=RMAN
   SQL>conn /as sysdba则可以成功连接到RMAN实例。
怀疑是listener.ora和tnsnames.ora文件的配置问题，但是找不到问题在哪里，困惑很久了，请各位大侠指点，感谢ing！

lsnrctl status?

C:\Documents and Settings\Administrator>lsnrctl status

LSNRCTL for 32-bit Windows: Version 10.2.0.3.0 - Production on 12-9月 -2011 07:4
1:48

Copyright (c) 1991, 2006, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.1.101)(PORT=1521
)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for 32-bit Windows: Version 10.2.0.3.0 - Produ
ction
Start Date                12-9月 -2011 07:37:20
Uptime                    0 days 0 hr. 4 min. 28 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   D:\oracle\product\10.2.0\db_1\network\admin\listener.o
ra
Listener Log File         D:\oracle\product\10.2.0\db_1\network\log\listener.log

Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.1.101)(PORT=1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(PIPENAME=\\.\pipe\EXTPROC0ipc)))
Services Summary...
Service "APPDBXDB" has 1 instance(s).
  Instance "appdb", status READY, has 1 handler(s) for this service...
Service "APPDB_XPT" has 1 instance(s).
  Instance "appdb", status READY, 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 "RMANXDB" has 1 instance(s).
  Instance "rman", status READY, has 1 handler(s) for this service...
Service "RMAN_XPT" has 1 instance(s).
  Instance "rman", status READY, has 1 handler(s) for this service...
Service "appdb" has 1 instance(s).
  Instance "appdb", status READY, has 1 handler(s) for this service...
Service "rman" has 1 instance(s).
  Instance "rman", status READY, has 1 handler(s) for this service...
The command completed successfully

C:\Documents and Settings\Administrator>

lsnrctl  service

你的listener配置没问题的~都是动态注册~
而且连接也是没问题的~

你的ORACLE_SID环境变量一次只能是一个值~而它和ORACLE_HOME会确定你连接的唯一的一个instance
当你的SID为APPDB的时候你肯定是无法连接RMAN的啊
你可以连接哪个实例的时候就把SID指向哪个~都连接的话就多几个窗口