Angular 2 http post request is not being called out

I am using angular 2 to make a get request and a post request. My get request works fine, but for my post, I do not see the request is made when checking my Firebug Net panel.

The code methods look like follows. I also have subscribe methods invoking them from a component class, which should not be relevant to this issue.

import {Injectable} from "angular2/core";
import {Http, Response, Headers, RequestOptions,  Jsonp, URLSearchParams} from "angular2/http";
import { Observable }     from 'rxjs/Observable';
import 'rxjs/add/operator/map'; 

 @Injectable()
export class MyService{
    constructor (private _http: Http){}  


testPost(){      

    var json = JSON.stringify({"userId": 111, "givenName": "CZ"});
    var body = "json="+json;
    var headers = new Headers({ 'Content-Type': 'application/json' });
    var options = new RequestOptions({ headers: headers });

    return this._http.post("http://mylocal.post.url", body, options)
        .map(this.extractData)
        .catch(this.handleError);

}

  private extractData(res: Response) {
    alert("test whether this method is reached");

    let body = res.json();
    return body.data || { };
  }

  private handleError (error: any) {
    alert("test whether this method is reached");

    let errMsg = (error.message) ? error.message :
      error.status ? `${error.status} - ${error.statusText}` : 'Server error';
    console.error(errMsg); // log to console instead
    return Observable.throw(errMsg);
  }     

 //testGet method is running well
testGet(link:string){

    return this._http.get(link)
    .map(res => res);

}     
}

I put an alert statement at the beginning of two helper methods. None of the alerts is reached. And I don't see any request called to the my local post url when debugging with Firebug.

While my testGet method works correctly, I just don't know what is missing for the testPost.