请教一个php连接oracle8.05的问题

[toolscool]

错误信息如下：
Warning: Unable to connect to ORACLE (Error while trying to retrieve text for error ORA-12154) in /data/httpd/htdocs/news/oracle.php3 on line 9

oracle.php3文件中第9 行为：
$count = ora_plogon("user@sid","password") or die;
$rs = ora_open($count);
ora_commitoff($count);

请这是什么原因？用户名口令和SID都是正确。谢谢。

[liyujie2000]

$conn = OCILogon("username", "password","SID");
$stmt = OCIParse($conn,"select table_name from user_tables");