If you do a phpinfo(), do you see the Oracle extension(s) being listed? If not, go recheck your PHP.INI. Also make sure to restart your webserver if running as a module instead of a CGI.
PHP generating a message about an undefined extension function usually means that the extension really isn't getting loaded. After successfully getting it to load, the next most likely problem is that the libraries that the extension relies upon are installed or aren't installed and configured correctly.
-- Michael
Darkstreak Computing & Innovations
www.darkstreak.com