Back button with tabs

Hi, i’m trying to make work navigation with tabs.

here is a jsfiddle with the issue:
http://jsfiddle.net/brayancastrop/fgcruwxg/1/

Right now when i go to an event the back button appears correctly in the nav bar, but when i go to a conference, the back button does not appear neither the transition animation.

Maybe i’m using wrong the tabs or missing something on the abstract state but i’ve tried using hide-back-button in the ion-view for each tab and tried to debug if history has something to do without luck :confused:

Please, any guidance will be apreciated.