AWS lambda: Unable to import application.application

Hi All,
I am new to serverless and I was using serverless to deploy a python flask application to AWS Lambda function with following instruction: https://serverless.com/blog/flask-python-rest-api-serverless-lambda-dynamodb/#converting-an-existing-flask-application. However I was getting following error

{ "errorMessage":"Unable to import application.application", "errorType":"Exception", "stackTrace":[ " File \"/var/lang/lib/python3.7/imp.py\", line 234, in load_module\n return load_source(name, filename, file)\n", " File \"/var/lang/lib/python3.7/imp.py\", line 171, in load_source\n module = _load(spec)\n", " File \"<frozen importlib._bootstrap>\", line 696, in _load\n", " File \"<frozen importlib._bootstrap>\", line 677, in _load_unlocked\n", " File \"<frozen importlib._bootstrap_external>\", line 728, in exec_module\n", " File \"<frozen importlib._bootstrap>\", line 219, in _call_with_frames_removed\n", " File \"/var/task/wsgi.py\", line 105, in <module>\n wsgi_app = import_app(config)\n", " File \"/var/task/wsgi.py\", line 49, in import_app\n raise Exception(\"Unable to import {}\".format(config[\"app\"]))\n" ] }

There is the serverless.yml file:
service: chromeagentapiservices

plugins:
  - serverless-python-requirements
  - serverless-wsgi

custom:
  wsgi:
    app: application.application
    packRequirements: false
  pythonRequirements:
    dockerizePip: non-linux

provider:
  name: aws
  runtime: python3.7
  stage: dev
  region: ap-southeast-2
  service: execute-api

functions:
  app:
    handler: wsgi.handler
    environment: 
      AppId: A string here
      Chrome_DB: another string here
    events:
      - http: ANY /
      - https: 'ANY{proxy+}'

Did I configure it correctly? Why does this issue happens?

FYI, I was building the app on Ubuntu

Were you able to resolve this?