SQL Function works in 5.0, not 4.4.1

Hi,
I have the following functions which work on my home server (IIS 5.0,
PHP5.1, MySQL 5) but not on the production server (Linux Apache Zend,
PHP 4.4.1, MySQL 4.1.13). From what I can see, I'm connecting to the
database, but the sql passed to it is not working on the prod server.
Any help would be much appreciated, I'm a newbie from .NET.
It may be difficult to read from the code below, but when I'm inserting
the variables into the sql string, I'm using double quotes then single
quotes as in:

' INSERT INTO ... " ' . $VARIABLE . ' "

Thank you in advance.

Jon

// test.php
include('users4x.php');
$users = new users();
$users->User_InsertNew('Jon', 'byrd', 'jb@nospam.net', 'byrd', '0');

// users4x.php
class users{

function User_InsertNew($UserFirstName, $UserLastName, $UserEmail,
$UserPassword,$ActInact){
        global $dbuser, $dbuserpass, $dbserver, $db;
        $sql='INSERT INTO `Users`(`UserFirstName`, `UserLastName`,
`UserEmail`, `UserPassword`, `ActInact`)
VALUES("'.$UserFirstName.'","'.$UserLastName.'","'.$UserEmail.'","'.$UserPassword.'","'.$ActInact.'");';
        $connection = mysql_connect($dbserver, $dbuser, $dbuserpass) or die
("Could not connect to server");
        $catalog = mysql_select_db($db);
        $result = mysql_query($sql);
        mysql_close();
}

}
Received on Tue Jan 3 03:50:40 2006