javascript debugger

I install the firefox extension. And it just shows up my tools menu with a option of "disconnect" and nothing else. I tried pointing the JS debugger in IDEA to my root url of the site (So I can debug any and all javascript?) but this doesnt seem to work.

How does one get this to work? can I only debug individual html files?  I have javascript in .js and .vm (velocity) files as well as html , php and my own custom extension. But nothing I do seems to want to debug.

Thanks for any help...