Please help!!! Can't connect PHP with MySQL

[Refon Miah]

I have installed PHP5 and MySQL 5 on my PC (running on Windows XP). My web server is Apache. However, i am experiencing problems in connecting PHP to MySQL.

Below is the script for my database connectivity:
__________________________________________________________________
<?php

function db_connect()
{
$result = new mysqli('localhost', 'bm_user', 'password', 'bookmarks');
if (!$result)
throw new Exception('Could not connect to database server');
else
return $result;
}

?>
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When i try to run this script, i receive a message saying - Fatal Error: Class 'mysqli' could not be found in ...'

Notes:

(1)I have added 'extension=php_mysqli.dll' to my php.ini file and uncommented it, but it has not made any difference.

(2)Also, when i run the script <?php phpinfo() ?>, there is no sections showing on MySQL or MySQLi.