Originally Posted by echino

Yours worked probably because you already have cards in both product lines. But if you have, for example, only charge card, like Amex Gold, and then self-refer to Amex Aeroplan Gold, then you are likely not going to get the referral bonus, because you had not had a pre-existing Aeroplan card to deposit bonus to. At least that's what is reported in the Amex forum.