We recognise many customers create a barcode immediately before shopping online. If /when you do this you may find that your online order is declined
Each time you create a barcode you are putting a 'hold' on those funds for use in-store for a period of 10 minutes. So if you try to shop online straightaway the funds are not available for use.
If you have created a barcode, you will need to wait 10 minutes before shopping online with Afterpay.