Bar does not show me I want


#1
 income even though the code to display a button on the header did not appear and the code it out of utoriales of ionic, I'm doing wrong?
    <ion-header-bar class="bar-positive">
      <h1 class="title">Contacts</h1>
      <div class="buttons">
        <button class="button button-icon ion-compose" ng-click="modal.show()">
        </button>
      </div>
    </ion-header-bar>
    
      <ion-content  has-header="true">swdw</ion-content>
  </ion-view>