title: Can't generate multi-axis combo chart (bar/line) using chart.js 2.7
body: <p>I've been having problems trying to generate a combo bar/line chart using chart.js 2.7.2.</p>
  
  <p>Currently I can render the chart, however the bars are not visible, as shown in the attached picture.</p>
  
  <p><a href="https://i.stack.imgur.com/FJqqO.png" rel="nofollow noreferrer">Combo Chart with problem</a></p>
  
  <p>Please note that in the above picture, "Data1" corresponds to the line chart to be plotted on the left Y axis, and "Data2" corresponds to the bar chart to be plotted on the right Y axis.</p>
  
  <p>Also note that the tooltip <strong>does</strong> show the "Data2" series, however it's not visible on the chart!</p>
  
  <p>Below the javascript code used to generate the chart. It uses a canvas within a simple html document.</p>
  
  <pre><code>    var x_time  = ['00:00', '00:30', '01:00', '01:30', '02:00', '02:30'];
      var y_data1 = ['99.83', '99.86', '99.81', '99.83', '99.72', '99.75'];
      var y_data2 = ['56', '41', '53', '46', '70', '60'];
      new Chart(document.getElementById('myChart').getContext('2d'), {
      data: {
          labels: x_time,
          datasets: [{ 
              type:'line',
              label: 'Data1',
              fill:false,
              backgroundColor: 'rgb(255, 99, 132)',
              borderColor: 'rgb(255, 99, 132)',
              data: y_data1,
              yAxisID: 'left-axis'
          }, {
              type: 'bar',
              label: 'Data2',
              fill: true,
              backgroundColor: 'rgb(54, 162, 235)',
              borderColor: 'rgb(54, 162, 235)',
              data: y_data2,
              yAxisID: 'right-axis'
          }]
      },
      options: {
          legend: {position:'bottom', usePointStyle:true},
          maintainAspectRatio:false,
          responsive: true,
          title: {display: false},
          tooltips: {mode: 'index', intersect: false},
          hover: {mode: 'nearest', intersect: true},
          scales: {
              xAxes: [{display: true, stacked:true, scaleLabel: {display: false, labelString: 'time'}}],
              yAxes: [{
                      type:'linear', 
                      id:'left-axis', 
                      display: true, 
                      position: 'left', 
                      scaleLabel: {display: true, labelString: '%'}
                      },{
                      type:'linear', 
                      id:'right-axis', 
                      display: true, 
                      position: 'right', 
                      stacked:false,
                      scaleLabel: {display: true, labelString: '#'}, 
                      gridLines: {drawOnChartArea:false}
                  }]
  
          }
      }
  });
  </code></pre>
  
  <p>Any help on this would be greatly appreciated.</p>