title: jqplot is using a different y scale for each series in a stacked barchart
body: <p><img src="https://i.stack.imgur.com/H7tdc.png" alt="enter image description here"></p>
  
  <p>I am using jqplot, why is the stacked barchart using a different Y scale for each series?</p>
  
  <pre><code>var ticks = ["test1", "test2", "test3", "test4", "test5", "test6", "test7", "test8", "test9"];
  var s1 = ["3", "3", "1", "3", "2", "3", "30", "3", "3"];
  var s2 = ["0", "0", "2", "0", "0", "0", "0", "0", "0"];
  
        plot3 = $.jqplot('daily-bookings-by-user', [s1, s2], {
          // Tell the plot to stack the bars.
          stackSeries: true,
          seriesDefaults:{
            renderer:$.jqplot.BarRenderer,
            rendererOptions: {
                // Put a 30 pixel margin between bars.
                barMargin: 20,
                // Highlight bars when mouse button pressed.
                // Disables default highlighting on mouse over.
                highlightMouseDown: true
            },
            pointLabels: {show: true}
          },
          axes: {
            xaxis: {
                renderer: $.jqplot.CategoryAxisRenderer,
                ticks: ticks
            },
            yaxis: {
              // Don't pad out the bottom of the data range.  By default,
              // axes scaled as if data extended 10% above and below the
              // actual range to prevent data points right on grid boundaries.
              // Don't want to do that here.
              padMin: 0,
              pad: 0,
              min: 0,
            },
          },
          legend: {
            show: true,
            location: 'e',
            placement: 'outside'
          },
          series:[
              {
                 label:'Test 1'
              },
              {
                 label:'Test 2'
              }
          ],
        });
  </code></pre>