Angular 2 http.post not posting

The DataService doesn't appear to be calling the Controller.

data.service.ts

import { Injectable, Inject } from 'angular2/core';
import { Http, Response } from 'angular2/http';
import 'rxjs/add/operator/map';
import {Observable} from 'rxjs/Observable';
import { TodoItem } from './TodoItem';

@Injectable()
export class DataService {

    constructor( @Inject(Http) public http: Http) {
        this.http = http;
    }

    getItems(): Observable<TodoItem> {
        return this.http.get('/api/todo').map((res: Response) => res.json());
    }

    addItem(item) {
        this.http.post('/api/todo', item);
    }
}

add-item.component.ts

import { Component, Inject } from 'angular2/core';
import { TodoItem } from './TodoItem';
import { DataService } from './data.service';

@Component({
    selector: 'add-item',
    template: `
    <input #item><button (click)=addItem(item.value)>Add</button>
  `
})

export class AddItemComponent {
    private item: TodoItem;

    constructor( @Inject(DataService) private dataService: DataService) {
        this.dataService = dataService;
        this.item = { Key: '', Name: '' };
    }

    addItem(item: string) {
        if (item) {
            this.item.Name = item;
            this.dataService.addItem(this.item);
        }
    }
}

app.component.ts

import { Inject, Component } from 'angular2/core';
import { DataService } from './data.service';
import { HTTP_BINDINGS } from 'angular2/http';
import { TodoItem } from './TodoItem';
import { AddItemComponent } from './add-item.component';

@Component({
    selector: 'app',
    bindings: [DataService, HTTP_BINDINGS],
    directives: [
        AddItemComponent
    ],
    template: `<h1>Hello World</h1>
<li *ngFor="#item of items">
  <span>{{item.Name}} {{item.Key}}</span>
</li>
<h4>Create</h4>
<p><i>Add a new hero</i></p>
<div><add-item></add-item></div>
`
})

export class AppComponent {
    public items: TodoItem[];

    constructor( @Inject(DataService) public dataService: DataService) {
        this.dataService = dataService;
    }

    ngOnInit() {
        this.dataService.getItems()
            .subscribe((items: TodoItem[]) => {
                this.items = items;
            });
    }
}