PDO fetch single class not working

i am making a database abstraction class that binds objects like an ORM. I'm having issue with a particular case, fetching a single row and binding to a class. While the same is working well with fetchAll() i can't figure out why using fetch(PDO::FETCH_CLASS) the object returns null. if i use PDO::FETCH_LAZY it works, but isn't a correct binding to the passed class. Here the code. The Database() class is connects to db using PDO. Products() is a class made of public attributes with same name of tables. The controller:

public function editProducts($params) {
    $products = new Products();
    $db = new Database ();
    $id = array_keys($params);
    $products = $db->findById($products, $id[0]); // auto Bind object fetched=no and POST params?
    $this->template = new Template();
    $this->template->renderArgs("product", $products);
    $this->template->renderArgs("page_title", "Edit product " . $products->title);
    $this->template->render(get_class($this), "editProducts");

}

The DB class:

public function findById($object,$id) {
    try {
    $table = $this->objectInjector($object);
    } catch (Exception $e) {
        if (APP_DEBUG) {
            d($e->getTrace());
        }
        return;
    }
    $statement = "SELECT * FROM $table WHERE id=:id";
    $this->stm = $this->pdo->prepare($statement);
    $this->bindValue(":id",$id);
    return $this->fetchSingleObject($object);
}

the method that abstract fetch:

public function fetchSingleObject($object) {
    $this->execute();
    $this->stm->setFetchMode(PDO::FETCH_CLASS, get_class($object));
    return $this->stm->fetch(PDO::FETCH_CLASS);
    //return $this->stm->fetch(PDO::FETCH_LAZY); this works!
}

I missed something? the fetchAll() works nicely in this way:

 public function fetchObjectSet($object) {
        $this->execute();
        $this->stm->setFetchMode(PDO::FETCH_CLASS, get_class($object));
        return $this->stm->fetchAll(PDO::FETCH_CLASS);
    }

Thank you so much. PS: some methods like $this->execute() are just abastractions to pdo->statment method since pdo and stm are db class instance variables.

via Chebli Mohamed