Bug Hover Not Producing AJAX Request

I'm not getting the AJAX request when hovering over a username on my custom skin (a slight modified default skin), though it does work on the default skin.

What code do I need to check is in the template?

On vB4 I am using $template_hook['headinclude_javascript'] in the headinclude template to place the script. It looks like individual usernames are getting their code replaced but I don't see the main script included in the headinclude
The plugin it's doing it with is PH: Append Global Javascript

I noticed after a change to the postbit it was working partially, will have a look over the headerinclude script shortly...