title: Highcharts error 15
body: <p>i'm trying to represent these data using highcharts:</p>
  
  <pre><code>[
    {
      "name": "c1",
      "data": [
        [
          -52587360000000,
          2
        ],
        [
          -52590038400000,
          1
        ],
        [
          -52611724800000,
          1
        ],
        [
          -52622611200000,
          1
        ],
        [
          -52655184000000,
          1
        ],
        [
          -52663392000000,
          2
        ],
        [
          -52855545600000,
          2
        ]
      ]
    },
    {
      "name": "c2",
      "data": [
        [
          -52587360000000,
          2
        ],
        [
          -52590038400000,
          1
        ],
        [
          -52611724800000,
          1
        ],
        [
          -52622611200000,
          1
        ],
        [
          -52655184000000,
          1
        ],
        [
          -52663392000000,
          2
        ],
        [
          -52855545600000,
          2
        ]
      ]
    },
    {
      "name": "c3",
      "data": [
        [
          -52587360000000,
          2
        ],
        [
          -52590038400000,
          1
        ],
        [
          -52611724800000,
          1
        ],
        [
          -52622611200000,
          1
        ],
        [
          -52655184000000,
          1
        ],
        [
          -52663392000000,
          2
        ],
        [
          -52855545600000,
          2
        ]
      ]
    }
  ]
  </code></pre>
  
  <p>This is what i try:</p>
  
  <pre><code>container.highcharts({
      title: {
          text:"Name"
      },
      xAxis: {
          type: 'datetime',
          dateTimeLabelFormats: {
              month: '%e. %b',
              year: '%b'
          }
      },
      yAxis: {
          title: {
              text: 'Occurrence'
          },
          plotLines: [{
              value: 0,
              width: 1,
              color: '#808080'
          }]
      },
      tooltip: {
          valueSuffix: 'Occurrence'
      },
      legend: {
          layout: 'vertical',
          align: 'right',
          verticalAlign: 'middle',
          borderWidth: 0
      },
      series: response // 
  });
  </code></pre>
  
  <p>The chart isn't shown correctly as you can see:
  <img src="https://i.stack.imgur.com/Wx6XA.png" alt="enter image description here">
  and in console i get this error:</p>
  
  <pre><code>"Highcharts error #15: www.highcharts.com/errors/15"
  </code></pre>
  
  <p>what is my error?</p>