Modal window vs product page differences

I have simple image slider for product images, but it only works in modal window. Why it's not working in full product page? What am I missing here? It did work fine on 1.36.

It only works if I add myscript to the box_product.inc.php and to the layout file "head" seaction. Otherwise it's not working.

Since 1.3.7 all JS in the body is extracted and moved to before closing the body. If your JS code is insertee to head_tags, add it to foot_tags instead - or just echo it straight on the page.