OK, I'm sure I'm missing something, but I can't for the life of me figure out the issue.
I've just installed the plugin, and tried to use one of the example shortcodes just to test it out before I start playing around with it. When I open the page it's on, though, I get just a blank space where the canvas should be, and the error "Uncaught ReferenceError: Chart is not defined".
The canvas is definitely being drawn; Firebug can select it, and it's moving the rest of the page down. It's just not generating the chart. Any idea what stupidly obvious thing I've missed?