Is this the right place to ask a question about Inception?

I just familiarized myself with the theory of the whole movie being a dream and there is something I don't understand about that theory:

If everything we see in the movie is just a dream why doesn't Mal appear in it the same way she does in other dreams against Copper's will and regardless of who's dreaming? Doesn't that indicate that Copper is right about when he is dreaming and when he is not?