Hello Kamryn,
The index.html file points to the mgr.js in the study folder.
It should work for any manager file that lays there.
One possibility is that you somehow changed the file layout (for example changed the study folder name, or changed mgr.js).
Another possibility is that you have some sort of error in your script. In order to check if that is the case, open developer tools and open your console (on many browsers you can press F12 as well).
best,
Elad