Should you be able to include and render an ss file from the theme /include directory from within an ss file located in the them /layout directory? Or can you only do this from within an ss file in the theme root?
1. /Layout/Tour.ss has <% include TourGallery %> in the code
2. I have a file with HTML in it in /Includes/TourGallery.ss
I can't get it to render.
I think that maybe I need to have Tour.ss in the root beside Page.ss and HomePage.ss
No you should have all your includes in the includes folder and then where ever you need be able to do <% include SuperCoolNewContent %> you can do. From inside a layout template or a root level template.
See the default theme - it includes the sidebar this way.