jQuery UI addClass(class, duration) not working

I am sure I have had this working before, but under jQuery UI 1.7.2 and 1.8.7 it appears that addClass(class, duration) is no longer working. I cannot even get the demo to work either (in any browsers).

I was using 1.7.2 up until a few minutes ago, when I upgraded. I swear I had it working last night, yet this afternoon it wasn't working so thought it best to upgrade first, before posting here. However I have had no luck in getting it working.

Is anyone else experiencing the same problem? Anyone had the same problem in the past and managed to solve it somehow?

If it is working for other people then I will post my code here, but at the moment I don't feel the need to do so as it will just take up space.

Thanks in advance.

Regards,

Richard

Example removed - replaced with http://jsfiddle.net/Z6mJU/. It appears to be working here, so maybe I don't have 开发者_Python百科jQuery set up correctly... I haven't fiddled with the masterpage much but apparently I have removed something vital, or so it seems. I will have another fiddle and see if I can solve it. Will post back here later with my progress.

I just had a similar issue with jQuery 1.5.1 and jQueryUI 1.8.12. I'd linked both libraries, but forgot to add in the bundled stylesheet. Adding to my header fixed the problem.