Alertpay is based in Canada and are a good company but some USA card holders can not use their card outside the USA so you will be automatically declined.
This is your bank preventing you from using your card because they are responsible to make sure you are not online gambling with that money. If you remember Bush put the Onus on the banks to watch over their customers to make sure they weren't gambling with their money so the banks cut off customers abilities to shop outside of America. In this case, your bank thinks you are trying to online gamble and wants to make sure they know you are not and so stopped you from using your card.
You may find this happens alot if you are trying to shop using an outside the US merchant
processor. I would imagine a online bank transefer would work to complete the order. We use Alertpay all the time and they are a great company and I am glad to use them.