Firebase write data

Ionic Framework ionic-v3
1

Hello, friends, i had created my mobile app successfully and installed all plugins successfully too.
But when i want to add data to firebase, its not adding data. Please check my codes and let me know what to do.

constructor(
    public alertCtrl: AlertController,       
    public modalCtrl: ModalController,
    public navCtrl: NavController,
    public toastCtrl: ToastController,
    public loadingCtrl: LoadingController
    ) {
        this.messageTable = firebase.database().ref('message');
        this.messageKey = this.messageTable.push().key;      
    }
writesendMessage(messageKey, nameField, emailField, phoneField, commentField){
 firebase.database().ref('message/' + messageKey).set({       
    Name: 'Faisal',
    Email: 'emy@gmail.com',
    Phone: '1234567890',
    Messaage: 'Hello, its just a test message',   
  });
//This code is adding the data to my database but showing the key as undefined
}

but when i use ngModel variables which are used in form

writesendMessage(messageKey, nameField, emailField, phoneField, commentField){
 firebase.database().ref('message/' + messageKey).set({       
    Name: nameField,
    Email: emailField,
    Phone: phoneField,
    Messaage: commentField   
  });
} //this code do nothing now, but few hours before it was showing me error.