You need to start over.
Here's the reason.
The default Screenset only has ONE page (default), and those controls are at the bottom of the page.
What you're calling "pages" are tabs of a tab control placed on the default page. When you change tabs, you're not changing pages, so you'll always see what's on the bottom.
Rich, I think that Z order only applies to objects that overlap. It just controls which objects are displayed on top of other objects (controls). It doesn't grey out or disable anything below something else.