Mass Effect 3 Leviathan

I downloaded the Leviathan dlc on my Xbox 360 and cannot access it. First off, I beat the game and have the save right before the start for the final mission attacking the illusive man's hideout. I've looked in my terminal, no message from hackett. I've looked in my mission logs, nothing about the citadel: Dr. Bryson mission. I've redownloaded this DLC 3 times and I cannot play it. This is irritating that EA has such terrible support that I can't even get a quick answer about this issue. I paid money for this DLC and I am getting PISSED that I cannot play it. If anyone has any possible answers I would love to hear them.