For me the roster sorting works on your site (Safari 5.1.7, Firefox 14.0.1), but I see, you have copied the raidplanner.css file into your template (there’s nothing wrong with that), but you forget to copy images files next to the CSS (sort-desc.png, sort-default.png, sort-asc.png are all missing).
What Web browser are you using?
15MtA5fPyKWn3c7J9NSSisSNZL3Qaz7ayU
