If you are in a country such as Argentina, you should call your bank and verify that your card is authorized for international purchases. Certain credit cards in that country (such as pre-paid credit cards) are ONLY authorized for domestic purchases and purchases in bordering countries. They DO work online, but the purchase must be from a bordering country. What this means is that you may get this message because your card is valid but denied. I know, because this has happened to me today. Hopefully this helps someone else understand what their system is telling them.