Custom Sidebar not displaying

Hi,
I have created a custom sidebar to display only posts from the Endorsements category on my site and attached it to the 'Book' page however, when I view the page the custom sidebar is not visible. I think I have created the sidebar correctly. I had a look at some of the posts from other users but none had any positive effect on my issue. I have granted support access should it be needed.

Thanks in advance

Chris Blair