Graphql schema always return null value from RDS Aurora Serverless

Hai.
i'm using reactjs for develop an app. then, appsync as graphql server and rds aurora serverless as database. after connecting all of components, i have problem with return value. value is always null like on picture.

here's my graphql schmea
`type Query{
listUsers: [user]
}`

here's my resolvers
request
`{
"version": "2018-05-29",
"statements": ["SELECT * FROM User"]
}`
and response
`$utils.toJson($utils.rds.toJsonObject($ctx.result)[0])`

here's the result from aws graphql console

thanks, i hope there a resolver to hlep me fixing the problem. i'am sorry about my language, thanks a lot.

Start with the GraphQL schema, the AppSync resolver request and response templates, and the AWS GraphQL console result shown in the issue. Trace the listUsers path through RDS Aurora Serverless and verify that the resolver returns the queried user values rather than null; done means the console returns populated values.

Written by the indexing model from the issue text.