I've installed the about us mod and created a further number of pages using this as a template (but changing the names).

When I'm in the admin and I use Define Pages Editor to edit a file, when I click save I get the following error message:

412 Precondition Failed
The precondition on the request for the URL /admin/define_pages_editor.php evaluated to false.
Do you think this is a permission issue or a setting I need to adjust in the admin?

All help appreciated!