There is an FAQ on the Dynamic Dropdowns Support page for this:
Q) Why is my layout incorrect after applying Dynamic Dropdowns?
A) The code inserted by Dynamic Dropdowns may have been placed outside (above) the <head> tag. Follow these steps to move the necessary code to the appropriate location:
1. In Dreamweaver, choose Code view.
2. From the Server Behaviors panel, select the Dynamic Array option.
3. Press Ctrl (Cmd) + X to cut the highlighted code from Code view.
4. Place your cursor below the <head> tag.
5. Press Ctrl (Cmd) + V to paste the code.