Back Button is not shown in Nav Bar in Android device

I am using the below code in my view. I am expecting to see Back button but I am not seeing it my actual device or even in any simulators.

Kindly let me know what I am missing.

<ion-view view-title="Upload">
    <ion-nav-bar class="bar-stable" align-title="center">

        <ion-nav-back-button>
        </ion-nav-back-button>

    </ion-nav-bar>

    <ion-content class="padding">
    </ion-content>
</ion-view>

ion-nav-bar and ion-nav-back-button are not children of ion-view.

Take a look at the tabs example

Thanks. Let me try and get back shortly.