Nette forms addupload neyoberie data

Ahojte, mam form:

protected function configure(\Nette\Application\UI\Presenter $presenter)
	{
		parent::configure($presenter);
		$this->addGroup();
		$this->addUpload('file', 'Nahrať súbor')
			->addRule(Form::IMAGE, 'Súbor musí byť JPEG, PNG alebo GIF.')
			->setRequired();
	}

ale ked ho chcem spracovat v>

public function submitProductForm(\FrontModule\Forms\ProductForm $form)
{
	$values = $form->values;
}

Dostanem cez dump:
file ⇒ array ()

Neviete co mi chyba, repsektive preco mi ten vybraty subor neberie? dakujem