Js tracking not working, image tracking ok.. why?

I have tried using the javascript tracking code but it doesn’t work.
It is correctly showed in the html, it doesn’t return any error on execution and the links to piwik.php work both in ssl and no-ssl.

To be sure the problem was only javascript I tried the image tracker code and it works!
Javascript is correctly working on my browser which is firefox and use it to view plenty of websites everyday.
What else can be?

The only strange configuration I have is that websites are hosted using
domain alias under Apache and dynamic IP service, however it shouldn’t matter as on the client side the browser simply see a URL as the correct domain (I have plenty of websites hosted this way and they don’t show any strange behaviour)

Any Idea?
Thank you

Solved!
Apparently the code inside parentheses of the javascript wasn’t correctly printed.
When using CMS like vanillaforums or cmsmadesimple you have to edit the template file under /themes/name_of_template/default.tpl and enclose the code inside {literal}{/literal}.
I think this should be added inside the FAQ because it wasn’t straightforward to see this little change in the output javascript code (indeed it doesn’t appear under source html but only in javascript re-written html).

Cheers.