Ngx-translate output problem

I used this tutorial

everything run , I can take json format but not print output

en.json

  {
    "HELLO": "hola",
    "hi":"sa"
  }
 constructor(public navCtrl: NavController, public navParams: NavParams, public translate: TranslateService) {
    translate.setDefaultLang('en');
  }
<div style="width: 100%;">           
        <p class="baslik">ACCOUNT</p>
      <button ion-item>
          <ion-label>{{ 'hi' | translate }}</ion-label>
      </button>
      <button ion-item>
          <ion-label>{{ 'hi' | translate }}</ion-label>
      </button>
  </div>

output;

hi

I believe you need to call translate.use(“en”) as well

I used but same problem