Form bound object properties remaining NULL

Controller

<?php
namespace NotaryRequest\Controller;

use Zend\Mvc\Controller\AbstractActionController;
use Zend\View\Model\ViewModel;
use NotaryRequest\Entity\Request;
use NotaryRequest\Form\CreateRequestUserForm;

class RequestController extends AbstractActionController
{
    public function addAction()
    {
        $vm = new ViewModel();
        $vm->setTemplate('notary-request/request/add.phtml');

        $sl          = $this->getServiceLocator();
        $em          = $sl->get('Doctrine\ORM\EntityManager');
        $form        = new CreateRequestUserForm($sl);
        /**
         * @var $httpRequest \Zend\Http\Request
         */
        $httpRequest = $this->getRequest();

        $requestEntity = new Request();
        $form->bind($requestEntity);
        if ($httpRequest->isPost()) {
            $form->setData($httpRequest->getPost());

            if ($form->isValid()) {
                \Zend\Debug\Debug::dump($form->getData());
                $em->persist($requestEntity);
                $em->flush();
            }
        }

        return $vm->setVariables(array(
            'form' => $form
        ));
    }
}

Fieldset

<?php
/**
 * @author    Manuel Stosic <manuel.stosic@duit.de>
 * @copyright 2013 DU-IT GmbH
 */
namespace NotaryRequest\Form;

use DoctrineModule\Stdlib\Hydrator\DoctrineObject;
use NotaryRequest\Entity\Request;
use Zend\Form\Fieldset;
use Zend\InputFilter\InputFilterProviderInterface;
use Zend\ServiceManager\ServiceManager;

class RequestFieldset extends Fieldset implements InputFilterProviderInterface
{
    public function __construct(ServiceManager $serviceManager)
    {
        parent::__construct('request-fieldset');
        $entityManager = $serviceManager->get('Doctrine\ORM\EntityManager');

        $this->setHydrator(new DoctrineObject($entityManager, 'NotaryRequest\Entity\Request'))
            ->setObject(new Request());

        $this->add(array(
            'type' => 'Zend\Form\Element\Hidden',
            'name' => 'id'
        ));

        $notaryFieldset = new NotaryPersonDataFieldset($serviceManager);
        $this->add($notaryFieldset);

        $contractFieldset = new ContractDataFieldset($serviceManager);
        $this->add(array(
            'type'    => 'Zend\Form\Element\Collection',
            'name'    => 'contracts',
            'options' => array(
                'count'                  => 1,
                'should_create_template' => false,
                'allow_add'              => true,
                'target_element'         => $contractFieldset
            )
        ));

        $this->add(array(
            'type'       => 'Zend\Form\Element\Select',
            'name'       => 'criteria',
            'options'    => array(
                'label'         => 'Ausschlusskriterium laut BauBG?',
                'empty_option'  => 'Bitte zutreffendes auswählen',
                'value_options' => array(
                    Request::CRITERIA_NONE                            => 'Nein, nichts zutreffend',
                    Request::CRITERIA_P24A2BAUBG_HERITATE             => '§ 24 Abs. 2 BauGB - Erbbaurecht',
                    Request::CRITERIA_P24A2BAUBG_OWNERSHIP            => '§ 24 Abs. 2 BauGB - Wohnungseigentum',
                    Request::CRITERIA_P26A1Z1BAUBG_FAMILY             => '§ 26 Abs. 1 Ziffer 1 BauGB - Verwandschaftsverhältnis',
                    Request::CRITERIA_P26A1Z2BAUBG_PUBLIC_OR_RELIGION => '§ 26 Abs. 1 Ziffer 2 BauGB - öffentliche oder religiöse Zwecke'
                )
            ),
            'attributes' => array(
                'required' => true,
            )
        ));

        $salesFieldset = new SalesPersonDataFieldset($serviceManager);
        $this->add($salesFieldset);

        $acquirerFieldset = new AcquirerPersonDataFieldset($serviceManager);
        $this->add($acquirerFieldset);

        $estateFieldset = new EstateFieldset($serviceManager);
        $this->add(array(
            'type'    => 'Zend\Form\Element\Collection',
            'name'    => 'estates',
            'options' => array(
                'count'                  => 1,
                'should_create_template' => false,
                'allow_add'              => true,
                'target_element'         => $estateFieldset
            )
        ));
    }

    /**
     * Should return an array specification compatible with
     * {@link Zend\InputFilter\Factory::createInputFilter()}.
     *
     * @return array
     */
    public function getInputFilterSpecification()
    {
        return array(
            'criteria' => array(
                'required' => true
            )
        );
    }
}

Form

<?php
/**
 * @author Manuel Stosic <manuel.stosic@duit.de>
 * @copyright 2013 DU-IT GmbH
 */
namespace NotaryRequest\Form;

use DoctrineModule\Stdlib\Hydrator\DoctrineObject;
use Zend\Form\Form;
use Zend\ServiceManager\ServiceManager;

class CreateRequestUserForm extends Form
{
    public function __construct(ServiceManager $serviceManager)
    {
        parent::__construct('create-request-user-form');
        $entityManager = $serviceManager->get('Doctrine\ORM\EntityManager');

        $this->setHydrator(new DoctrineObject($entityManager, 'NotaryRequest\Entity\Request'));

        $requestFieldset = new RequestFieldset($serviceManager);
        $requestFieldset->useAsBaseFieldset(true);

        $this->add($requestFieldset);

        $this->add(array(
            'type' => 'Zend\Form\Element\Csrf',
            'name' => 'duitsecutiry'
        ));

        $this->add(array(
            'type' => 'Zend\Form\Element\Submit',
            'name' => 'createRequestSubmit',
            'attributes' => array(
                'id'    => 'formsubmit',
                'value' => 'Antrag einreichen',
                'class' => 'btn btn-large btn-success'
            )
        ));
    }

}