oralce客户端连不上服务器问题

[yanfan8312002]

我的电脑装了oralce客户端，可以ping通服务器ip（192.168.1.100），但是用pl/sql developer登录不了服务器，错误是：ORA-12535 TNS 操作超时。我连了几次都这样。我的tnsnames.ora配置文件如下：

DMISDB100 =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.100)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = DmisDB)
)
)

请教高手，这是什么原因啊！！

[真的不知道取什么名]

端口号是对的不？
服务名写对了没有

[lzbbob1985]

DMISDB100 =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.100)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = DMISDB100)
)
)

[yanfan8312002]

端口号、服务名都写对了，我把服务器上的配置文件下面这段拿过来也不行啊！
DMISDB =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.100)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = DMISDB)
)
)

[yanfan8312002]

是防火墙问题，还是感谢各位！