Problem with Angular and Firebase

I'm trying to create an application with Angular and Firebase, I followed a guide I found on the internet, but the data is not being stored in the database!

Follow the component code akael.service.ts

import { Injectable } from '@angular/core';
import{ AngularFireDatabase, AngularFireList } from 'angularfire2/database'


import { Akael } from './akael.model'

@Injectable()
export class AkaelService {

  selectedAkael : Akael = new Akael();
  akaelList: AngularFireList<any>;

  constructor(private firebase : AngularFireDatabase) {

  }
   getData(){
     this.akaelList = this.firebase.list('models');
     return this.akaelList;
   }

   insertAkael(akael : Akael){
     this.akaelList.push({
       nome: akael.nome,
       sigla: akael.sigla,
       descricao: akael.descricao
   });
   }

   updateAkael(emp : Akael){
     this.akaelList.update(emp.$key,{
       nome: emp.nome,
       sigla: emp.sigla,
       descricao: emp.descricao
     })
   }

  deleteAkael(key : string){
    this.akaelList.remove(key);
  }
}

Register-model.ts component code

import { Component, OnInit } from '@angular/core';
import { NgForm } from '@angular/forms'

import { AkaelService } from '../shared/akael.service'

@Component({
  selector: 'app-register-model',
  templateUrl: './register-model.component.html',
  styleUrls: ['./register-model.component.css']
})
export class RegisterModelComponent implements OnInit {

  constructor(private akaelService: AkaelService) { }

  ngOnInit() {
    this.resetForm();
  }


  onSubmit(form: NgForm){
    if(form.value.$key == null)
      this.akaelService.insertAkael(form.value);
    else
      this.akaelService.updateAkael(form.value);
    this.resetForm(form);
  }

  resetForm(form? : NgForm){
    if(form != null)
      form.reset();
    this.akaelService.selectedAkael = {
      $key: null,
      nome: '',
      sigla: '',
      descricao: '',
    }
  }

  onDelete(form: NgForm){
     if(confirm('Are you sure to delete this record? ')==true)
  {
     this.akaelService.deleteAkael(form.value.$key);
     this.resetForm(form);
  }
 }
}