It doesn't seem like you should be running into this problem, but DreamHost prevents domains from being moved between hosting accounts when the destination account is a promo coded or referral account. This is to prevent people moving their hosting to a new promotional account every year and getting hosting for the $22.40 introductory rate forever.
As I said, from how you've described your situation, since you've never hosted the domain here, this shouldn't be a problem, but you never can tell. Have you submitted a support ticket?
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