Local notification i can not get out any sound? HELP?

This is my code but it does not play any sound… what is wrong?
IONIC 4

import { Component } from '@angular/core';
import { LocalNotifications } from '@ionic-native/local-notifications/ngx';
import { Storage } from '@ionic/storage';
import { NavController, AlertController, Platform } from '@ionic/angular';
import { ToastController } from '@ionic/angular';

@Component({
  selector: 'app-home',
  templateUrl: 'home.page.html',
  styleUrls: ['home.page.scss'],
})

export class HomePage {
  constructor(
    public navController: NavController,
    public navCtrl: NavController,
    private plt: Platform,
    private localNotifications: LocalNotifications,
    private alertController: AlertController,
    private toastController: ToastController) {



      this.localNotifications.on('trigger').subscribe(notification => {
          this.presentToast();
      });
      this.localNotifications.on('yes').subscribe(notification => {
          this.presentAlert(notification.data.meetingId);
      });
      this.localNotifications.on('no').subscribe(notification => {
          this.presentAlert(notification.data.meetingId);
      });
    }


// TRIGGER
  async presentToast() {
    const toast = await this.toastController.create({
      message: 'Stop the Sound!',
      duration: 2000
    });
    toast.present();
  }


  async presentAlert(test) {
    const alert = await this.alertController.create({
      header: 'Alert',
      subHeader: 'Subtitle',
      message: test,
      buttons: ['OK']
    });

    await alert.present();
  }



// On load or every check!
  scheduleNotification() {
    this.localNotifications.schedule({
          id: 1,
          led: { color: '#FF00FF', on: 500, off: 500 },
          title: 'Spela upp Athan - 1',
          text: 'Abdelbaset Athan spela upp.',
          trigger: {at: new Date(new Date().getTime() + 3000)},
          data: { meetingId:"Athan - 1" },
          sound: 'file://assets/sms.mp3',
          actions: [
            { id: 'yes', title: 'Ok, fortsätt lyssna!' },
            { id: 'no',  title: 'Stopa Athan' }
          ]
      });
  }


}