Spring Transaction

I want to know more about transactions in spring. I have the following structure:

My Service:

@Service
@Transactional
public class MinhaClasseServiceImpl implements MinhaClasseService {

    @Autowired
    private MinhaClasseDao minhaClasseDao;

    @Autowired
    private OutraClasseDao outraClasseDao;

    @Autowired
    private MaisOutraClasseDao maisOutraClasseDao;

    public void salvarMinhaClasse(final MinhaClasse minhaClasse) throws Exception {
           maisOutraClasseDao.salvarMaisOutraClasse(minhaClasse().getOutraClasse().getMaisOutraClasse());
           outraClasseDao.salvarOutraClasse(minhaClasse().getOutraClasse());
           minhaClasseDao.salvarminhaClasse(minhaClasse());
    }

}

But when saving, an exception is thrown:

11:11:33,766 ERROR [stderr] (default task-13) javax.persistence.PersistenceException: 
org.hibernate.PersistentObjectException: detached entity passed to persist: 
com.teste.entity.MaisOutraClasse

Is the transaction not propagating? Can anyone help me?