[Ionic beta 11] PopoverController gives TypeError: Cannot read property 'create' of undefined

Here is my code

import {Component} from '@angular/core';
import {App, Page, Modal, Alert, NavController, LoadingController, PopoverController} from 'ionic-angular';
import moment from 'moment';

  template: `
      <button ion-item (click)="close()">Learn Ionic</button>
      <button ion-item (click)="close()">Documentation</button>
      <button ion-item (click)="close()">Showcase</button>
      <button ion-item (click)="close()">GitHub Repo</button>

class PopoverPage {

  constructor(ViewController) { this.viewCtrl = ViewController; }

  close() {

export class SamplePage {
constructor(app, nav, locationData, LoadingController, PopoverController) {
this.popoverCtrl = PopoverController;

openPopoverMenu(event) {
    let popover = this.popoverCtrl.create(PopoverPage);
    popover.present({ ev: event });

and then I don’t know why when I click on the popover icon, the browser reports the error

ORIGINAL EXCEPTION: TypeError: Cannot read property ‘create’ of undefined

Why is my popoverCtrl is undefined?

Any help is appreciate. Thanks!

@menshinobi if you are using JS (not TypeScript) please add:

static get parameters() {
    return [
      [IonicApp], [NavController], [LocationData], [LoadingController], [PopoverController]

to your class.