Javascript mysteriously stopped working

I have been using the twisty (from Peter Grainge's site) in my Help topics as part of a Related Topics link. I use the twisty next to the words 'Related Topics', and then create a drop down hot spot of both the image and text. When the user clicks the image or the text, the list of related topics expands and the arrow changes to point down. I have created 17 projects with this in and all is fine. I have a template with this in and always add the down.gif and twisty.js to the baggage files (although the twisty.js does have to be added by editing the rhbag.apj file). I have gone to create another project and the javascript just won't work. I have tried creating a topic with the template and also by manually typing in the extra lines of code needed. The necessary files are in the baggage files but it just won't work. There is no error when you click on 'Related Topics' - you just see the links but no change in the arrow. I have tried importing a topic from a project that does work but this stops working. I have tried renaming a working project to trick it into being another project but this doesn't work either. I am really stuck. Hoping someone can shed some light. Thanks