Problème fonction vote

<?php
try
{
$pdo_options[PDO::ATTR_ERRMODE] = PDO::ERRMODE_EXCEPTION;
$db = new PDO('mysql:host=localhost;dbname=main', 'root', '',
$pdo_options);

$nbvote = $_GET['nvote']++;
$req=$db->prepare('UPDATE sugg set vote =:vote where sug =:sug');
$req->BindValue(':vote',$nbvote);
$req->BindValue(':sug',$_GET['sug'], PDO::PARAM_STR);
$req->Execute();
header('location: ./index.php');
}
catch(Exception $e)
{
die('Erreur : '.$e->getMessage());
}
?>