Why if I have the title attribute nothing shows up on the app (?)

I am using ion-tabs and the last version of Ionic framework, as you can see here at the bottom there are 3 options: Home, About, Contact.

I want to display something similar in my app, the icons are displaying correctly but with no title.

this is what I am getting instead of this

and here my code:

 <ion-tabs class="tabs-positive tabs-icon-only">

  <ion-tab title="Straight" icon-on="ion-android-arrow-forward" icon-off="ion-ios-arrow-thin-right" ng-click="showBetType('displayStraight')">
    Straight
  </ion-tab>
  <ion-tab title="Parlay & Robin" icon-on="ion-ios-loop-strong" icon-off="ion-ios-loop" ng-click="showBetType('displayParlayRobin')">
    Parlay & Robin
  </ion-tab>
  <ion-tab icon-on="ion-ios-redo" icon-off="ion-ios-redo-outline" ng-click="showBetType('displayParlayIfBet')">
    If & Reverse
  </ion-tab>
  <ion-tab icon-on="ion-arrow-shrink" icon-off="ion-arrow-expand" ng-click="showBetType('displayParlayTeaser')">
    Teaser
  </ion-tab>

</ion-tabs>

That class is the cause.
Replace that with tabs-icon-top