IonicPrevious-title-button not Shown sometime

ionic-v1
1

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Capture.PNG1242×707 311 KB 

    <ion-nav-buttons side="right">
          <a  href="#/app/search/Classifieds"> <button  class="button button-icon icon ion-ios-search" style="color:white" ></button></a>
    </ion-nav-buttons>

i wrote like that

2

image
Capture1.PNG1262×684 293 KB

somtime like this ,
check this out in inspect element ,it show .hide class in button tag