Problem using radio group in ionic 3

Ionic Framework ionic-v3
1

Am trying to use a radio box in my ionic app but I can’t see my options.
here’s a sample:
ft
here’s my ts file:

import { Component } from '@angular/core';
import { IonicPage, NavController, NavParams } from 'ionic-angular';
import { Validators, FormBuilder, FormGroup, FormControl,AbstractControl } from '@angular/forms';



@IonicPage()
@Component({
  selector: 'page-param',
  templateUrl: 'param.html',
})
export class ParamPage {


  langs;
  langForm;


public todo:FormGroup;  
  constructor(public navCtrl: NavController,public navParams: NavParams, private formBuilder: FormBuilder) {
  
    this.langForm = new FormGroup({
      "langs": new FormControl({value: 'rust', disabled: false})
    });


}


doSubmit(event) {
  console.log('Submitting form', this.langForm.value);
  event.preventDefault();
}`` `

// and here my html file:

<ion-header>
    <ion-navbar>
        <ion-title>
            Paramétres
        </ion-title>
    </ion-navbar>
</ion-header>

<ion-content>

    <form (submit)="doSubmit($event)" [formGroup]="langForm">
        <ion-list radio-group formControlName="langs">

            <ion-list-header>
                Language
            </ion-list-header>

            <ion-item>
                <ion-label>Go</ion-label>
                <ion-radio value="golang" checked="true"></ion-radio>
            </ion-item>
            <ion-item>
                <ion-label>Rust</ion-label>
                <ion-radio value="rust"></ion-radio>
            </ion-item>
            <ion-item>
                <ion-label>Python</ion-label>
                <ion-radio value="python"></ion-radio>
            </ion-item>
            <ion-item>
                <ion-label>Ruby</ion-label>
                <ion-radio value="ruby"></ion-radio>
            </ion-item>
            <ion-item>
                <ion-label>Clojure</ion-label>
                <ion-radio value="clojure"></ion-radio>
            </ion-item>
            <ion-item>
                <ion-label>Java</ion-label>
                <ion-radio value="java"></ion-radio>
            </ion-item>
            <ion-item>
                <ion-label>PHP</ion-label>
                <ion-radio value="php"></ion-radio>
            </ion-item>
            <ion-item>
                <ion-label>.NET</ion-label>
                <ion-radio value="dotnet"></ion-radio>
            </ion-item>
            <ion-item>
                <ion-label>C++</ion-label>
                <ion-radio value="cplusplus"></ion-radio>
            </ion-item>
            <ion-item>
                <ion-label>Scala</ion-label>
                <ion-radio value="scala"></ion-radio>
            </ion-item>
            <ion-item>
                <ion-label>Haskell</ion-label>
                <ion-radio value="haskell"></ion-radio>
            </ion-item>
            <ion-item>
                <ion-label>Erlang</ion-label>
                <ion-radio value="erlang"></ion-radio>
            </ion-item>
        </ion-list>
    </form>

</ion-content>
what am doing wrong here?