PDOException not working in try/catch

[GMD]

Using a PDO data object, even when the query fails, it never throws an exception(not even a generic one). Does anyone know why?

 

try
{
    $result = $this->db->query($sql);
}
catch(PDOException $e)
{
    $this->exit_page('Database Errorrr', $e->getMessage());
}