EJB and nullpoint exeption with Conversation Scoped

I have a big very problem. I'm using Netbeans IDE 7.4 with Java EE 6. Whenever I try to persist an Entitie. It throws me

Advertencia: #{controlador.save}: javax.ejb.EJBException: javax.ejb.EJBException: javax.ejb.CreateException: Could not create stateless EJB javax.faces.FacesException: #{controlador.save}: javax.ejb.EJBException: javax.ejb.EJBException: javax.ejb.CreateException: Could not create stateless EJB........... Caused by: java.lang.NullPointerException

But whenever I try to use SessionScoped and others Scopes. It doesn't throw me and error. Here is the code of my farcade.

   @Stateless
public class Users1Facade extends AbstractFacade<Users1> {

    @PersistenceContext(unitName = "PruebaEJBPU")
    private EntityManager em;
    @Override
    protected EntityManager getEntityManager() {
        return em;
    }

    public Users1Facade() {
        super(Users1.class);
    }

    @Override
    public void create(Users1 entity) {

        getEntityManager().persist(entity);
    }  

}

And Here is the code of my Controler

@Named
@ConversationScoped
public class Controlador implements Serializable{
    private Users1 user=new Users1();
    @EJB
    private Users1Facade facade;
    @PostConstruct
    public void init()
    {        

    user=new Users1();

    user.setName("qqq");
        user.setApellido("rwerwe");
    user.setId(32);
    }
    public String a()
    {
        facade.create(user);
        return "index";
    }

This error only throws me with Conversation Scoped. And I need to use that scope.It's damn annoying.