The request was denied due to request throttling. Please verify the number of requests made per second to the Amazon Product Advertising API

Why I am getting following error although running it only for one ASIN. There is only request in 24 hrs. not too many requests. Can anybody from Amazon support look into it?

As per my knowledge the allowed requests are 86400 in a day and 1 per second, so not able to understand if I request for getting details of 1 ASIN in 24 hrs., why I am getting this error.

{ "__type": "com.amazon.paapi5#TooManyRequestsException", "Errors": [ { "Code": "TooManyRequests", "Message": "The request was denied due to request throttling. Please verify the number of requests made per second to the Amazon Product Advertising API." } ] }