title: highcharts tooltip wrong date
body: <p>I had made one highchart in that tooltip is shows date and time in format but it is showing wrong date and time.</p>
  
  <p>Please go through the code below.</p>
  
  <h2>HTML Code</h2>
  
  <pre><code>&lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"&gt;&lt;/script&gt;
  &lt;script src="http://code.highcharts.com/highcharts.js"&gt;&lt;/script&gt;
  &lt;script src="http://code.highcharts.com/modules/exporting.js"&gt;&lt;/script&gt;
  &lt;div id="container" style="min-width: 310px; height: 400px; margin: 0 auto"&gt;&lt;/div&gt;
  </code></pre>
  
  <h2>Javascript Code</h2>
  
  <pre><code>var maxval="94";
  $(function () {
  var chart;
  $(document).ready(function() {
      chart = new Highcharts.Chart({
  
      credits: {
          enabled: false
      },  
      chart: {
          type: 'column',
          renderTo: 'container',
      },
      title: {
          text: 'Weekly Traffic'
      },
      xAxis: {
          type: 'datetime',
          labels: {
              format: '{value:%d-%b-%Y}',
              rotation:-45,
          },
      },
  
      yAxis: {
          labels:{enabled: false},
       title: {
                text: ''
             },
      }, 
  
            tooltip: {
                  formatter: function() {
                          return '&lt;b&gt;'+ this.series.name +'&lt;/b&gt;&lt;br/&gt;'+': '+Highcharts.dateFormat('%Y-%m-%d %H:%M', this.x) +'&lt;br&gt;'+   Highcharts.numberFormat((this.y /maxval ) * 100) + '%';
                  }
              },
  
      plotOptions: {
          line: {
           enableMouseTracking: false
          },
  
          series:{
           pointStart: 1444242600000,
          pointInterval: 86400000,
               shadow:false,
           dataLabels:{
              enabled:true,
              formatter:function()
                  {
                  var pcnt = (this.y /maxval ) * 100;
                  return Highcharts.numberFormat(pcnt) + '%';
                  }
              }
          }    
  },
  
      series: [{
          name: 'Firefox',
          data: [10,56,32,12,64,13,38],
      },{
          name: 'Chrome',
          data: [52,59,10,60,94,3,8],
      },{
          name: 'Edge',
          data: [22,56,20,35,14,73,38],
      },{
          name: 'Opera',
          data: [30,36,80,65,44,53,81],
      },{
          name: 'Safari',
          data: [40,16,50,77,34,33,36],
  
      }],
  
      });
  
  });
  
  });
  </code></pre>
  
  <p>The working fiddle is given
  <a href="http://jsfiddle.net/w0dn75qu/4/" rel="nofollow">here.</a></p>