xp下的php 连oracle 问题

phporacle

Warning: oci_connect() [function.oci-connect]: OCIEnvNlsCreate() failed. There is something wrong with your system - please check that PATH includes the directory with Oracle Instant Client libraries in D:\PHPnow\htdocs\hfgh\ct2\3.php on line 13
这个错误 怎么解决啊？