помогите исправить sql запрос чтобы он на нюке сработал?

<?
// Add Admin Voting database field(s)
// Version 1.1.8 ErDrRon@aol.com http://www.ErDrRon.com/phpBB2/
//
// N.B. This script installs the necessary database field for the Admin Voting MOD.
// This script will only work with a mySQL database. Only use this script
// for the initial installation of the MOD. If you are re-installing the MOD
// or updating the version of the MOD, DO NOT run this script! Delete this
// script from your webserver after successful installation of the MOD.

// Connect to phpbb database
//
include('./config.php');
$cnx = mysql_connect($dbhost, $dbuser, $dbpasswd)
or die("Unable to connect to database server.");
mysql_select_db($dbname, $cnx)
or die("Unable to select database.");

// Add field 'vote_cast' to database table 'vote_voters'
//
$sql = "ALTER TABLE " . $table_prefix . "vote_voters " .
"ADD vote_cast TINYINT( 4 ) UNSIGNED " .
"DEFAULT '0' NOT NULL";

$result = mysql_query($sql);
if(!$result)
echo "Install failed<BR><BR>";
if (mysql_error()) { echo "Error Report: <B>".mysql_error()."</B><BR><BR>"; }
else
{
echo "Install complete: Admin Voting database field added successfully.<BR><BR><BR>Remember to delete this script ASAP.";
}
exit;
?>