Ah, um .. you may find that you've been caught in the dreaded "Email Zone". Email addresses are coupled to device serial numbers for whatever reason.
Did you apply a NEW email address to the new unit that you received, or did you try to use the old email address? Your map subscription is probably tied to the old address. Unless you made special provisions with Customer Service to transfer your old email address to your new serial number, your map updates are waiting for someone with the old serial number and email address (paired) to log in.
Call them and let them know what happened, and they will either reassign your old email to your new unit, or have you re-register your new unit with a different email address so that the server will correctly identify you when you login to the MyTomTom web page.