Doctrine a gedmo ako rozchodit tree?

Caute, snazim sa rozchodit tree na gedmo, nemate niekto priklad zakladnej facade? Lebo som sa uz zasekol tu a neviem v com je problem. ked zavolam:

$categoryTree = $this->categoryFacade->childrenHierarchy();

tak mi to zacne nadavt:Call to a member function childrenHierarchy() on a non-object,
Vsimol som si ze repoUtils je null a nikde sa nenastavuje, nejako ste to dodatocne konfigurovali?
Za akukolvek radu dakujem.

Zatial mam fasadu len v tomto stave:

class CategoryFacade extends Gedmo\Tree\Entity\Repository\NestedTreeRepository
{
	/** @var EntityDao */
	private $dao;

	/** @var  EntityManager */
	private $em;


	/**
	 * @param EntityManager $em
	 */
	public function __construct(EntityManager $em)
	{
		$this->dao = $em->getDao(Category::getClassName());
		$this->em = $em;
	}


	/**
	 * @return EntityDao
	 */
	public function getDao()
	{
		return $this->dao;
	}


	/**
	 * @param Category $entity
	 * @return array|Category
	 */

	public function save(Category $entity)
	{
		$this->em->persist($entity);
		$this->em->flush();
	}
}