I've done it before so I know it can happen. But it's not easy; in fact very difficult. That's why you don't see so many people talking about it, but if you hang out enough in these types of forums you will see reports of this.
It is difficult to do for many reasons- the dreamspace has mental barriers usually, which is why you usually have to have permission by the other person to do this, and both people have to remember to be able to verify it. Even then, it's difficult. But not impossible.

but can you try again as the system has recently changed i would love to know if you are successful again, the system is designed to keep out all intruding for all in many many areas in fact all areas, dont worry a system will be constructed for all areas for such events to take place safely and securely without any unwanted intruders, im sure your aware this has been a problem in the past in many areas!
like ya said permission by the other party, so if ya could try doing that now see what happens, their is a process their for such events (asking permission) but im not sure whether thats good enough maybe that could be minipulated (in a short time), the whole idea of it is to make it as simple as possiable even for the novice and safety being number one, maybe a system that you Ap into a area and pick what ya want, i know that all that is done by human beings talked about on sites as this is all recordered, we want to make a system so as you are able to pick it of the shelf so to speak and away ya go

good luck
love all