title: Useing amChart serias
body: <p>We have created something like this, and now I wont to add some periods to my chart <a href="https://codepen.io/sarkis-bagramqn/pen/MPjdLK" rel="nofollow noreferrer">codepen</a>. but the code that I wrote doesn't work.  Thank you</p>
  
  <p><a href="https://i.stack.imgur.com/peP0I.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/peP0I.png" alt="enter image description here"></a></p>
  
  <pre><code>    am4core.useTheme(am4themes_animated);
        let items = [
          {
            "X": 1,
            "Y": 2,
            "code": "ExecDate",
            "date": "May 06, 2010",
            "enabled": true,
            "name": "Execution Date",
            "refTxt": null,
            "refX": null
          },
          {
            "X": 1,
            "Y": -1,
            "code": "EffDate",
            "date": "May 07, 2010",
            "enabled": true,
            "name": "Effective Date",
            "refTxt": null,
            "refX": null
          },
        ....
        ];
  
        let periods = [
          {
            "Xend": "May 08, 2010",
            "Xstart": "May 07, 2010",
            "Y": 1,
            "code": "PunchPeriod",
            "name": "Punch List Completion Period"
          },
          ...
        ];
  </code></pre>
  
  <p>Please help me</p>