angular2-google-maps with angular2 app

这是app.module.ts

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AppComponent }  from './app.component';
import { AgmCoreModule} from 'angular2-google-maps/core';
@NgModule({
  imports:      [ BrowserModule,AgmCoreModule.forRoot({apiKey: 'AIzaSyAe3ci9yavJcWt7MaJE8DusAuZo-QeRqkU'}) ],declarations: [ AppComponent ],bootstrap:    [ AppComponent ],})
export class AppModule { }

我用命令安装了angular2-google-maps,

npm install angular2-google-maps --save

哪个成功安装.当我用npm start运行应用程序时,
它显示错误说,

07001 Failed to load
resource: the server responded with a status of 404 (Not Found)

但我可以在node_modules中看到angular2-google-maps文件夹.
问题是什么？