$ formulaire-> isvalid dit que ce n'est pas valide, mais mon formulaire ne montre aucun message d'erreur - Zend Framework 2

J'ai un problème avec l'addition dans mon application CRUD. Sur le contrôleur, la logique ne transmet pas la vérification $ formes-> isvalid (), mais le formulaire ne montre aucun message d'erreur.

J'ai essayé avec ceci (merci Sam): P>

class ProductController extends AbstractActionController
{

    protected $productTable;
    protected $brandTable;

    public function indexAction()
    {
        return new ViewModel(array(
            'products' => $this->getProductTable()->fetchAll(),
        ));
    }

    public function addAction()
    {
        $formManager = $this->serviceLocator->get('FormElementManager');
        $form = $formManager->get('Administrador\Form\ProductForm');
        $form->get('submit')->setValue('Add');

        $request = $this->getRequest();
        if ($request->isPost()) {
            $product = new Product();
            $product->brand = new Brand();
            $form->setInputFilter($product->getInputFilter());
            $form->setData($request->getPost());

            if ($form->isValid()) {
                $product->exchangeArray($form->getData());
                $this->getProductTable()->saveProduct($product);

                // Redirect to list of products
                return $this->redirect()->toRoute('product');
            }
        }
        return new ViewModel(array(
            'form' => $form,
        ));
    }

    public function editAction()
    {
        $id = (int) $this->params()->fromRoute('id', 0);
        if (!$id) {
            return $this->redirect()->toRoute('product', array(
                    'action' => 'add'
            ));
        }

        // Get the Product with the specified id.  An exception is thrown
        // if it cannot be found, in which case go to the index page.
        try {
            $product = $this->getProductTable()->getProduct($id);
        }
        catch (\Exception $ex) {
            return $this->redirect()->toRoute('product', array(
                    'action' => 'index'
            ));
        }
        $formManager = $this->serviceLocator->get('FormElementManager');
        $form = $formManager->get('Administrador\Form\ProductForm');
        $brand = $this->getBrandTable()->getBrand($product->brand);
        $product->brand = $brand;
        $form->bind($product);
        $form->get('submit')->setAttribute('value', 'Edit');

        $request = $this->getRequest();
        if ($request->isPost()) {
            $form->setInputFilter($product->getInputFilter());
            $form->setData($request->getPost());

            if ($form->isValid()) {
                $this->getProductTable()->saveProduct($form->getData());

                // Redirect to list of products
                return $this->redirect()->toRoute('product');
            }
        }

        return array(
                'id' => $id,
                'form' => $form,
        );
    }

    public function deleteAction()
    {
        $id = (int) $this->params()->fromRoute('id', 0);
        if (!$id) {
            return $this->redirect()->toRoute('product');
        }

        $request = $this->getRequest();
        if ($request->isPost()) {
            $del = $request->getPost('del', 'No');

            if ($del == 'Yes') {
                $id = (int) $request->getPost('id');
                $this->getProductTable()->deleteProduct($id);
            }

            // Redirect to list of products
            return $this->redirect()->toRoute('product');
        }

        return array(
                'id'    => $id,
                'product' => $this->getProductTable()->getProduct($id)
        );
    }


    public function getProductTable()
    {
        if (!$this->productTable) {
            $sm = $this->getServiceLocator();
            $this->productTable = $sm->get('Administrador\Model\ProductTable');
        }
        return $this->productTable;
    }

    public function getBrandTable()
    {
        if (!$this->brandTable) {
            $sm = $this->getServiceLocator();
            $this->brandTable = $sm->get('Administrador\Model\BrandTable');
        }
        return $this->brandTable;
    }
}