It will work. Let understand the concept of comments.
– You may enable or disable comments for any page or post via Screen Options. Make sure Discussion is checked for a page. OR Following article will be helpful to you regarding to enable / disable comments.
Let create another page for Guest Book say “Guest Book New Page”
Make sure Comments are enabled for this page
Publish it by selecting Full Width Page
See the Results. If you are still unable to set up Guest Book than i will email you personally to set it up for you