Conditional text not removing extraneous pages

[karyn hunt]

Hi,
 
  I'm using conditional text to single source from one doc to another. Specifically, I'm referencing a file from one book into another and removing several sections by conditioning them out. This leaves several pages empty. In one circumstance, the book/PDF automatically removes the extra pages when I run the PDF. In another case, it doesn't. Why is one leaving extra pages and another isn't? And how do I fix this?
 
Karyn