oracle connectivity problem

hi, I am facing a strange problem. I have oracle 8.1.6 (server) installed on linux and am trying to access it thru PHP from a client machine (again Linux). I was successful in making connections to the Oracle Server through programs written in C and Perl. But everytime i execute some program written in PHP it throws back an error. "Fatal error: Call to undefined function: ocilogon() in /usr/local/apache/htdocs/test.php " in test.php i am calling ocilogon as: ocilogon ("scott","tiger",$db); I have installed PHP with oracle support. phpinfo() shows that oracle support is enabled and it identifies ORACLE_HOME and ORACLE_SID. Please tell me where i am going wrong TIA regards Rajiv