How to return Async ActionResult to another controller action?

I have two controllers: A is obtained from AsyncController, B is from the controller. A has DoAsync and DoCompleted methods. I need to return from the action of the action of controller B from the action of the action of Do of A controller without redirecting. If I try to just return A.Do () from the action in the B controllers, null is returned. (I am using T4MVC)