Did you assign a drop down to the other pages within the page?
Go to page attributes (to the right or bottom of the page you want in the drop down). Select the parent page it should fall under, then select the *order* it should appear.
You can also go into Appearance, Menus, create a Custom Menu, then go to the pages box, and select your pages. When you see the pages appear in the custom menu list, you can drag and drop the child pages *slightly* to the right.