The most common cause of errors when trying to pay for your order with Bitcoin is that your purchase amount is less than $5. As of December, 22nd 2017 Bitpay requires a minimum of $5 to process your transaction. You will either need to add more to your cart or choose an alternate payment method.
This requirement was put in place by BitPay and SMOKEA cannot make any exceptions to their policies.
If your cart total is greater than $5 and you are still getting an error please contact your bitcoin wallet issuer.