App version not showing

Hi There,

I am trying to show the App version number, and I think I set it up correctly, but nothing is shown.
This what I have done so far:

In the app.module.ts, I included:

import { AppVersion } from '@ionic-native/app-version';

Then in the same file, at the providers, added:

AppVersion

Then on the contacts.ts file, added again:

import { AppVersion } from '@ionic-native/app-version';

Then added the following:

export class ContactPage {
  contact: string = "contactus";
  versionNumber: '0.0.1';

  constructor(private appVersion: AppVersion,public navCtrl: NavController) {
    this.appVersion.getVersionNumber().then((version) => {
      this.versionNumber = version;
    })
  }
}

And the contact.html:

{{versionNumber}}

Am I missing something?