In your Checkout by Amazon:
Make sure you verfiy your Account
Make sure you Verify your Payment Methods.
To get your Merchant ID and Access Key:
Your Merchant ID:
Your Checkout by Amazon merchant ID as displayed within the "Settings" -> "Checkout Pipeline Settings" area of the Seller Central control panel.
Access Key ID:
Your Checkout by Amazon merchant key as displayed within the "Integration" -> "Access Key" area of the Seller Central control panel.
