angularFire2 and ionic2

Ionic Framework ionic-v3
1

Hi, hope you guys are well.
i’m facing a little issue using angularfire2, when i load my angularfire function , i have a white screen , anyone already used angulafire2 in her/his app , and can tell what to do in this case , or in general how can i manage to do what i want to do.

import {Page} from 'ionic-angular';
import FirebaseService from '../../services/firebase.service'
import TaskService from '../../services/task.service'
import TaskThread from '../../model/thread.model';
import {ChangeDetectionStrategy, ChangeDetectorRef} from 'angular2/core'
import {AngularFire, FIREBASE_PROVIDERS, defaultFirebase} from 'angularfire2';
import {Observable} from 'rxjs/Rx'


@Page({
  templateUrl: 'build/pages/page1/page1.html',
  providers: [FirebaseService, TaskService, FIREBASE_PROVIDERS, defaultFirebase('https://FUBRL.firebaseio.com')],
})
export class Page1 {
  tasks: TaskThread[]=[]
  currentUserID: any
  ref: any
  messages: Observable<any>
  constructor(public TaskService: TaskService, public FirebaseService: FirebaseService, private af: AngularFire) {
    this.currentUserID = this.FirebaseService.rootRef.getAuth().uid;
    this.ref = this.FirebaseService.rootRef;
    this.loadUn()
  }


  // load(){
  //   this.TaskService.loadTask().subscribe(data => {
  //
  //   })
  // }

loadUn(){
  return this.af.list(this.ref.child("messages").orderByKey().equalTo("-KEMOXVugOQqlvLd-epW"))
}



}

this is what my integration look like