Seem like it might not be aggregating properly with a timeseries axis. I have two categories in the data (I can pass you the output). The data is "Date" each week (on a Sunday). The total Task count should be much higher.
// chart 1
var svg = dimple.newSvg("#chartContainer1", 800, 450);
var myChart = new dimple.chart(svg, data);
myChart.setBounds(60, 50, 650, 300);
var x = myChart.addTimeAxis("x", "Date", "%Y-%m-%d", "%d %b %y");
x.timePeriod = d3.time.weeks;
x.floatingBarWidth = 15;
var y1 = myChart.addMeasureAxis("y", "Tasks");
var s = myChart.addSeries("Approval Hops", dimple.plot.bar);
s.addOrderRule(["10+","6-10","4","3","2","1"]);
myChart.assignColor("0", "#B3DE69", "#95b957", 0.8);
myChart.assignColor("1", "#B3DE69", "#95b957", 0.8);
myChart.assignColor("2", "#B3DE69", "#95b957", 0.8);
myChart.assignColor("3", "#fdb462", "#d39651", 0.8);
myChart.assignColor("4", "#fdb462", "#d39651", 0.8);
myChart.assignColor("5", "#fdb462", "#d39651", 0.8);
myChart.assignColor("6-10", "#fb8072", "#d26b5f", 0.8);
myChart.assignColor("10+", "#fb8072", "#d26b5f", 0.8);