Redmine

I want to create a child page and try follwing the FAQ

These relations can be set by assigning a parent page to a to-be child-page. This assignment can be done via the rename dialog only.
Thus, create both the child- and parent-pages and then open the to-be child-page and click "rename", then select the name of the parent page and click "save".

But when I open the "rename" page there is nothing where I can select a parent page. Only the edit field for the title, a checkbox to rename links also and a button start renaming.

Is there something to configure before I can use child pages

We use redmine version 1.3.*

Thanks in advance