mysql_connect undefined

I had Apache 1.3.22, PHP 4.0.6, and MySql 3.23.41 all working fine together under RH 7.2. I then made the mistake of installing Zend Studio Server and PHP can no longer access MySql when run from Apache. When I access a .php page through apache I get this error: Fatal error: Call to undefined function: mysql_connect()... But if I execute php on the command line with the same file it works correctly and the html I would expect is written to stdout. So can someone tell me why php would produce this error when run through Apache? This is a URL to phpinfo() if it helps: http://dev.robotbattle.com/hello.php -Brad