Can't get at.js to work

Hi,
I am using the latest version of Harmony (Core, access, askimet, hide user, search, moderation, access) and would like to use the at.js feature.

I have installed the library at the required location:

$ ls -1 sites/all/libraries/
at.js
caret.js

There is no error message in the back-end, that the files are not found. In addition, there is no error in the chromium javascript console while loading the page with the create thread form. I am missing any reference to the at.js and caret.js scripts in the page source code. The only harmony related javascript loaded is

.../sites/all/modules/harmony_hide_user/harmony-hide-user.css?...

Is there any configuration stuff I need to do to get this working?
Do you need additional information for helping me?

Kind regards,
Eike