new admin cannot see correct VIP Portal

I'm in the process of moving a number of users from one VIP to another, so we only have one active. I've set up the admin of the defunct account as an admin on the combined one, however, he cant see it at all. Following the email link just takes him into his old account, and the new account isn't visible to him anywhere. We've run the process the other way, making me an admin of his account, and that worked fine. Any idea what's wrong?