FormGroup and ReactiveFormModule does not detect a hidden field of my form

Friends of StackOverflow as I do so that in angular 5 and ReactiveForm I detect a field in hidden.

This is my code for my component.

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';
import { HttpClient, HttpHeaders } from "@angular/common/http";

declare var $: any;

@Component({
  selector: 'index-body',
  templateUrl: './body.component.html',
})
export class BodyComponent implements OnInit {

  wantPackageForm: FormGroup;

  // VIDEO EJEMPLO DE FORMS --> https://www.youtube.com/watch?v=bo1Wu0aiigU

  constructor (private fb: FormBuilder, private httpClient: HttpClient) {

    this.wantPackageForm = fb.group({
      'inputName': [null, [Validators.required, Validators.minLength(6)]],
      'inputEmail': [null, Validators.compose([Validators.required, Validators.email])],
      'inputPhone': [null, [Validators.pattern('[0-9]+'), Validators.required, Validators.minLength(10), Validators.maxLength(10)]],
      'inputMessage': [null, [Validators.required, Validators.minLength(25)]],
      'inputPackage': [null, Validators.minLength(6)],
    });

  }

  public submitWantPackageForm(post) {

    let data = {
      name: post.inputName,
      email: post.inputEmail,
      phone: post.inputPhone,
      message: post.inputMessage,
      pkg: post.inputPackage
    };

    console.log("FROM ANGULAR");
    console.log(data);

    this.httpClient.post("http://localhost:9200/api/save_want_package", data)
      .subscribe(
        (data: any) => {

          console.log("FROM NODE");
          console.log(data);

          if (data.status == 200) {
            alert('Solicitud enviada correctamente');
            this.wantPackageForm.reset();
          } else {
            alert('Falla al enviar la solicitud: ' + data.message);
          }

        }
      );
  }

  /***********************************************************************/
  /***********************************************************************/


}