How to get data from AWS dynamoDB

As the title, I’d like to know how to get the data from my Dynamo DB.
I have already create a Dynamo DB table and API Gateway . and I also could post data to my database by using API Gateway. But I can’t get the data from my database.
It is work on my API gateway TEST , but not work in my UE4 project.
following are my test and UE4 log screenshot.
any help would be greatly appreciated .