insert mysql

Jeg har følgende script:

<?
include('connect.php');

if (isset($_POST['newmail'])) {
    if($emne=='') {
        print('<script type="text/javascript">window.location="index.php?info=Fejl"</script>');die();
}
    $emne = $_POST['emne'];
    $sql = 'INSERT INTO invite_mail (id, to, from, emne, mail) VALUES ("", "'.$_POST['to'].'", "'.$_POST['from'].'", "'.$_POST['emne'].'", "'.$_POST['mail'].'")';
    echo "DEBUG: " . $sql . "<br>";
        mysql_query($sql) or die("Kunne ikke forbinde : " . mysql_error());
        echo "<font face='Verdana' size='1'>Mail til $to sendt.</font>";
    }

?>

Men får denne fejl:

DEBUG: INSERT INTO invite_mail (id, to, from, emne, mail) VALUES ("", "1", "5", "fg", "dgdf")
Kunne ikke forbinde : You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near 'to, from, emne, mail) VALUES ("", "1", "5", "fg", "dgdf")' at l