QnA component

Summary

i want to cretae a bot only using System.QnA component to make my bot reply to some question.

Content

i want to build a sample of a Q&A bot. i created the bot and uploaded the csv file and every thing is ok but one i am using the bot tester i always get a response from the unresolved state. here my OBotML code: 

metadata:
  platformVersion: 1.0
main: true
name: QnA_Bot
context:
  variables:
states:   
  qna:
    component: "System.QnA"
    transitions:
      actions:
        none: "unresolved"
      next: "qna"
  unresolved:
    component: "System.Output"
    properties:
      text: "Sorry, I did not find any match. Can you rephrase the question?"