Body onload events do not work in framework pages
Had occasion to use Dynamic Dropdowns today in part of an admin panel I am building using framework builder to pull in the various pages and on the update page I needed to use the set selected in list behaviour to populate the category and subcategory dropdown lists and it took me a good 5 minutes to figure out why my page was not working !
Framework builder doesn't pull any body onload events in.
It might be worth considering changing the method you use here so that onload events are put in the head of the document rather than the body tag in future.