title: Highcharts x-axis datetime issue
body: <p>in my javascript I defined how to populate a <code>LineChart</code> of <code>Highcharts</code>. This is populated with the data given by a database. The x-axis of the chart is of <code>datetime</code> type and the x-value is <code>DateTime</code> type.</p>
  
  <pre><code>xAxis: {
       type: 'datetime',
       labels: {
              formatter: function () {
                 return Highcharts.dateFormat('%d %b - %H:%M:%S', this.value);
              }
       }
  },
  
  
  lineCharts[index].series[roiIndex].addPoint([point.creationDateTime, point.result]);
  </code></pre>
  
  <p>but what I see is the following:</p>
  
  <p><a href="https://i.stack.imgur.com/TNRoY.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/TNRoY.png" alt="chart"></a></p>
  
  <p>I can't find the solution..does anyone have an idea? Thanks!</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>Now creationDateTime is the epoch time expressed in milliseconds:</p>
  
  <pre><code>DateTime date = roi.created_at;
  var epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
  var creationDateTimeEpoch = Convert.ToInt64((date - epoch).TotalMilliseconds);
  </code></pre>
  
  <p>infact, the value is <a href="https://i.stack.imgur.com/FLWPa.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/FLWPa.png" alt="this one"></a> that converted with <a href="https://www.epochconverter.com/" rel="nofollow noreferrer">https://www.epochconverter.com/</a> corresponds to the correct value. But now I see the series <a href="https://i.stack.imgur.com/kipVo.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/kipVo.png" alt="in this way"></a>.</p>