CanvasJS requires the container’s height and width to be set in order to render. While BootStrap sets width of the container based on the class(span6, span10, etc) that you set, it doesn’t set the height. Hence the problem. Just set the height of the container (or Chart) and it should work fine.
<div class=”span10″ id=”chartContainer” style=”height: 400px;”></div>