Number of "bound variables" does not match the number of "tokens"

What was done: I just added a select to save the data in the database. The script:

    if(!empty($_GET['codusuario']) && $_SERVER['REQUEST_METHOD'] == 'GET'){
    $stm = $pdo->prepare('SELECT * FROM usuario WHERE codusuario = ?');
    $stm->bindParam(1, $_GET['codusuario'], PDO::PARAM_INT);
    $stm->execute() or die(implode('', $pdo->errorInfo()));

    $_POST = $stm->fetch(PDO::FETCH_ASSOC);
}

if($_SERVER['REQUEST_METHOD'] == 'POST'){
    if(empty($_POST['codusuario'])){
        $sql = 'INSERT INTO usuario (email,senha,chave,select2,pergunta) VALUES (?, ?, ?, ?, ?)'; //email, senha, chave, pergunta
        $stm = $pdo->prepare($sql);
        $stm->bindParam(1, $_POST['email']);
        $stm->bindParam(2, $_POST['senha']);
        $stm->bindParam(3, $_POST['chave']);
        $stm->bindParam(4, $_POST['select2']); //@new select box
        $stm->bindParam(5, $_POST['pergunta']);

        $stm->execute();
    } else {
        $sql = 'UPDATE usuario SET email = ?, senha = ?, chave = ?, pergunta = ? WHERE codusuario = ?';
        $stm = $pdo->prepare($sql);
        $stm->bindParam(1, $_POST['email']);
        $stm->bindParam(2, $_POST['senha']);
        $stm->bindParam(3, $_POST['chave']);
        $stm->bindParam(4, $_POST['pergunta']);
        $stm->bindParam(5, $_POST['codusuario'], PDO::PARAM_INT); //old number is 5
        $stm->bindParam(6, $_POST['select2']);
        $stm->execute();
    }

    header('Location: index.php');
    exit;
}