When you sign up with the PayPal debit card, what do you enter for "State" and "Zip Code"? From what I can see the PP debit card is registered to our Canadian address and so the same problem arises when trying to fill out the online form.
We contacted Endicia and the rep wasn't very helpful, they offered very little in the way of assistance in this. They said we could sign up using the address of the post office in Blaine, Washington, but didn't have any suggestions on how to pay.
Cheers,
Ernie.