Making nested AWS::ApiGateway::Resource failed in Resources

Serverless Framework
1 
resources:
  Resources:
    APIProxyResourceParent:
      Type: AWS::ApiGateway::Resource
      Properties:
        ParentId:
          Fn::GetAtt:
            - ApiGatewayRestApi
            - RootResourceId
        PathPart: api
        RestApiId:
          Ref: ApiGatewayRestApi
    
    APIProxyResource:
      Type: 'AWS::ApiGateway::Resource'
      Properties:
        ParentId: !Ref APIProxyResourceParent
        PathPart: '{proxy+}'
        RestApiId: !Ref ApiGatewayRestApi

    APIProxyMethod:
      Type: 'AWS::ApiGateway::Method'
      Properties:
        ResourceId:
          Ref: APIProxyResource
        RestApiId:
          Ref: ApiGatewayRestApi
        HttpMethod: any
        RequestParameters:
          method.request.path.proxy: true
        Integration:
          IntegrationHttpMethod: any
          Type: HTTP_PROXY
          Uri: 'https://dev-api.scinapse.io/{proxy}'
          IntegrationResponses:
            - StatusCode: 200

I made above resources attributes in serverless.yml, and confirm it is validate one in cloudformation designer.

however, it always make below two errors.

Invalid Resource identifier specified (Service: AmazonApiGateway; Status Code: 404; Error Code: NotFoundException;

The following resource(s) failed to create: [APIProxyResource, ServerlessDeploymentBucketPolicy].

what should I do for these error?