Why does Amazon's Product Advertising API return “Request from blacklist…is throttled.”?

Question

I have a registered key from Amazon's Product Advertising API (formerly ECS). I query the API to get information about the product listing for my mobile application. It was working perfectly fine. Today I have noticed that the API returns

"Request from blacklist...is throttled".

I am well within the API call limit. What could be the reasons for this message? Has anyone experienced this?

Answer 1

I still dont know on what basis Amazon API black listed me. But i have figured out a solution around it. Make a new key pair.