连接远程数据库报错“ora-12154:tns:无法解析指定的连接标识符”?报错

刚装完了oracle，安装过程很顺利，可是在客户端就是连不上，看不出来有什么问题，请教各位大神

pl/sql developer 报错：“ora-12154:tns:无法解析指定的连接标识符”

装在CentOS 6.5 上的oracle 12C R1

两个机器可以互ping

# listener.ora Network Configuration File: /u01/app/oracle/product/12.1.0/dbhome_1/network/admin/listener.ora
# Generated by Oracle configuration tools.

listener.ora 文件如下：
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBANAME = venn.server.world)
      (ORACLE_HOME = /u01/app/oracle/product/12.1.0/dbhome_1)
      (SID_NAME = venn)
    )
  )
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
  )
tnsnames.ora 文件如下：

# tnsnames.ora Network Configuration File: /u01/app/oracle/product/12.1.0/dbhome_1/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.


LISTENER_VENN =
  (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
VENN =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.220.131)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = venn.server.world)
    )
  )

执行lsnrctl start 输出的最后一段：

<p>
	Services Summary...<br>

Service "venn" has 1 instance(s).
  Instance "venn", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully