How to build subpage navigation?



I have an issue with sub-views navigation in my 3tabs application
In one of the tab, I’d like to have a page that contains 2 subviews accessible with their own url.

I used an abstract state for the “parent view”, and 2 substates for the subviews.
This parent view has a nav-title and nav-buttons, they should not be animated when navigating between subviews.

However, as demonstrated in this plunker, the title and the buttons are not displayed in the ABOUT tab.
Does anyone has a clue ? Thanks in advance !