Have you tried the code in Firefox? It's pickier about standards, so if
you get it to work there, it's very likely to work in IE also. The main
reason that I ask, however, is because of the nice error reporting in
Firefox. The Error Console shows any Javascript errors that occurs (as
well as CSS errors), and by clicking it you can view the exact code
causing the error.

Another option is enabling script debugging in IE and run the
application in debug mode from Visual Studio. That should let you debug
the Javascript.

(For debugging in Firefox, have a look at the Venkman project.)