You have problem at checkout, no worry this is really easy fix.
there are the cummon causes
No default Billing and Shipping address
AVS miss match
1. When you click on "Agree & Place Order" and nothing happen?
This is probably because you do not have Billing and Shipping address set in your account.
1. Shipping Address missing
2. Shipping Methods missing
If you have this on checkout, it mean your address is not set in "My Account"
2. You received this error message
We now use AVS verification that make sure the Card Holder match the billing addrress.
It is not every online store that us AVS but we decided to use it because to prevent possible fraud.
Possible causes are :
Someone else card
Prepaid card
VISA debit
Because the billing address does not match the card holder address as explain in the warning. To solve this issue download your credit card statement to ensure it is the same.