title: Trouble using DC.js (crossfilter and d3 convenience library) - bar chart not showing values
body: <p>I am using this library: <a href="http://nickqizhu.github.io/dc.js/" rel="nofollow noreferrer">Dimensional Charting</a> to build some relatively standard charts that need CrossFilter functionality.</p>
  
  <p>I have been following the examples but they aren't working for me.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>var dashData = crossfilter(data.report),
  dataByHour = dashData.dimension(function(d){ return d3.time.hour(new Date(d.timestamp))}),
  totalByHour = dataByHour.group().reduceSum(function(d) { return d.amount }),
  
  dc.barChart("#graphTimeOverview")
      .width(990) // (optional) define chart width, :default = 200
      .height(250) // (optional) define chart height, :default = 200
      .transitionDuration(500) // (optional) define chart transition duration, :default = 500
      .margins({top: 10, right: 50, bottom: 30, left: 40})
      .dimension(dataByHour) // set dimension
      .group(totalByHour) // set group
      .elasticY(true)
      .centerBar(true)
      .gap(1)
      .x(d3.time.scale().domain([new Date(data.report[0].timestamp), new Date(data.report[(data.report.length - 1)].timestamp)]))
      .round(d3.time.hour.round)
      .xUnits(d3.time.hours)
      .renderHorizontalGridLines(true);
  
  dc.renderAll();
  </code></pre>
  
  <p>I know the crossfilter data is working correctly, here is a sample of the group:</p>
  
  <pre><code>totalByHour:
  
  [ {key:(new Date(1361746800000)), value:6170.17},
    {key:(new Date(1361678400000)), value:3003},
    {key:(new Date(1361581200000)), value:2350.42}, 
    {key:(new Date(1361667600000)), value:1636.19},
      etc... 
  ]
  </code></pre>
  
  <p>Unfortunately all this gets me is an empty graph, it seems to compute the y-axis correctly, so it would seem to me that it can read the data, however I never see any bar values:</p>
  
  <p><img src="https://i.stack.imgur.com/Hcj1H.png" alt="enter image description here"></p>