Your example code is fine, but your JSFiddle has an issue with script references. In the Chrome console I see this:
Refused to execute script from 'https://bitbucket.org/cleonello/jqplot/raw/e8af8a37f0f14ea1e8c630ecfe6f1b1933794036/src/plugins/jqplot.canvasAxisLabelRenderer.js' because its MIME type ('text/plain') is not executable, and strict MIME type checking is enabled.
I removed that reference and added a link to http://cdn.jsdelivr.net/jqplot/1.0.8/plugins/jqplot.canvasAxisLabelRenderer.min.js and it works OK. See modified example here: