On the consumer end of an eCommerce transaction, these days, clicking the buy button is usually the end of the road. Usually, the transaction goes through, the widget goes into the mail and everyone goes to bed happy. Sometimes, the card gets declined, the consumer gets frustrated, moves on and the merchant misses the sale.
Now, if there was legitimately something amiss with the card — it happened to be stolen, for example — then that rejection is a good thing, because, by rejecting the transaction, the merchant avoids the dreaded chargeback.