Replacing the navbar for a view

Hello,
I followed the doc http://ionicframework.com/docs/api/directive/ionNavBar/ “Alternative Usage” to replace the navbar for a specifiv view, but doesn’t seem to be working.

Here is an example:

Click on “Scientific Facts” -> the bar shoud show a back button “back”.
Then click on “More Facts” -> in the code this view has another navbar with a “back 2” back button, but it isn’t recognized.

Am I missing anything or is there a bug?

Any ideas about that? Otherwise I’ll submit a bug report for this issue, because the nav bar replacement doesn’t seem to be working or the documentation is wrong.