No Charge on USPS Shipping

Hello,

Just went live with my marketpress store today.

I'm having problems with the USPS shipping. Two customers from Canada (I'm in the US) and another from Arizona were not charged shipping.

I also received an email from a potential customer in Finland and he was not getting a shipping calculation when he entered his address information. I tired this myself (for his address in finland) and it did not load shipping information for me either but I was allowed to go to the checkout page (using PayPal Express)

I However have 4 orders that did process fine with shipping charges, all being in the US.

What I've done in the mean time is to allow only US orders.

Also I am using Priority and Express for both Domestic and International, I am not using any flat rate options.

How can I get this resolved.