Ionic call modal from inside of `ion-tab`


I suppose there much be something specific about this case, as it is suppose to work.

The problem is simple - i can’t open modal from the content of ion-tab
i have a google map in ion-tab and trying to call a modal from the click at the google map marker.

here is the related code:
call itself:

export class MapMainTabPage {
  @ViewChild('map') mapElement: ElementRef;

  constructor(private modalCtrl:ModalController, private userData: UserData, private events: Events, private mapService: MapService, private condoService: CondoServiceProvider) {


  ionViewDidLoad() {
    if (this.userData.getLocation()){
    else {'user:location:set', ()=>{this._setupMap()})
    console.log('ionViewDidLoad MapMainTabPage');

      this.mapService.placeMarkers(data, this.callLocationItemsModal)

    console.log("callLocationItemsModal(), id: ", location_id);
    let myModal = this.modalCtrl.create('MapLocationModalPage', {condoId: location_id});

=> the callLocationItemsModal called properly with the marker id passed into it.

But the modal throwing an error:

Uncaught TypeError: Cannot read property 'modalCtrl' of undefined
    at webpackJsonp.251.MapMainTabPage.callLocationItemsModal (map-main-tab.ts:44)

what is wrong?