Here's the problem,
I've purchased The Shivering Isles for Oblivion long ago on a separate account while it was gold. The account is now silver but that does not take away the fact that I can download. The trick is that the account I'm downloading with was on a different xbox. I used "recover account" on my new xbox without a problem at all. Using the silver account that I just recovered, I downloaded Shivering Isles and other DLC for Oblivion. After the downloads were completed I got on my new gold account and tried to play but the DLC never loaded (but it had the Shivering Isles achievements enabled). After the DLC did not work, I went on to my silver account and played the game, and it had no problem at all. I know that DLC does work for more accounts that just one. As long the account that downloaded it is on the same xbox as the other.
Additional Info:
Oblivion is installed to an external memory unit.
