Drag and Drop Question

I used one the custom drag and drop templates to create a drag and drop assessment questions with 5 drop targets and draggable items.  When I scroll down the page a white space appears at the bottom of the screen and my drag items fly back each time I tried to drag it to the drop target.  When I scroll up the white space at the bottom disappear and all of my drag items function properly.  I have removed the primary footer and the white space still appear. How do I remove the white space that is causing my drag and drop to malfunction?