Navigation Panel for TOC is Empty

The navigation panel does not show anything for the Table of Contents for my book. Book is T h e  H e a l t h  E d u c a t i o n  S p e c i a l i s t : A  C o m p a n i o n  G u i d e  f o r  P r o f e s s i o n a l  E x c e l l e n c e.

The book has a TOC but it does not show in the Navigation Panel. Bookmarks i've created to show.

How can I get it to work?