in's Creed: Brotherhood Da Vinci DLC Messing up?

I am having problems with the Da Vinci DLC and need some help. My brother has downloaded the DLC through his gamer profile on our Xbox and it works for him fine, but for me on the other hand, it's a mess. Alright, at first it wouldn't let me play my own saved file (I had played the DLC on a friends Xbox) but then I redownloaded on my brother's account and it worked fine, but I have to do that every time I get on an want to play, which is okay, I guess. The big problem is I don't get the multiplayer stuff out of it, and I am an AC multiplayer and need it. It worked on all the other xbox's I've had but it doesn't work for me. If anyone could help with this problem it would be highly appreciated.