Ralph Asset Management System - User Group

How to use RalphTemplateView?

Hello,
I’m trying to create a new template for my app, how I could see I can do this adding to my view a class with a new element: RalphTemplateView, also adding this view to url.py and a specific function in admin.py. Later, in the file sitetrees.py in ralph_item I could add this view, but I receive an error message in ‘access _by perms’, it says: “ValueError: Permission does not exist.”. So i’m not sure if i’m doing an error trying to implement RalphTemplateView or if I need other method to add a new template for my app.
I’d like to find somebody who could help me to arrange this error or could give any advice to try another method.
Thank you