Ok, geni It's difficult, I know. well, "Да" means Yes "Нет" means NO "Конечно" means Certainly buuuuuut, all together they mean NO, and you say that when you're 100% sure that you're right. Tricky, isn't it? just the way we speak
by the way "Да" can also mean just "and", so you're right anyway it quite hard to figure out though, the real answer, whether it's yes or no.