PHP and Oracle - PHP_OCI8.DLL

Hi, I installed PHP4.0.4.pl1 (from binaries from www.php.net) on my Win98 machine with Apache 1.3.12. Everything works well until I try to connect to my Oracle database. After loading php_oci8.dll I get an error message telling me that PHP is unable to find necessary files to load this module. Unfortunatelly it doesn't say what are these files. I set the ORACLE_HOME variable and it didn't help. I tried to change some settings in conf files but it wouldn't help neither. Could please someone tell me what these files might be, or how could I check this by myself? What should I do to install this module? I also tried php_ora.dll but it says the same thing. I tried to find something in the web, but couldn't find anything about this problem. Is this the problem with my Oracle installation or with PHP? I use Oracle 8i Personal Edition 8.1.6r2 for Win98. The OCI that comes with this database is of course installed. I'd be grateful for any help, Mike Siwak