Typescript Angular2 模块没有导出成员

对于Angular2中具有身份验证的网站，我想使用主应用程序组件中身份验证子模块的一个组件.然而，我不断得到以下错误:

app/app.component.ts(3,10): error TS2305: Module '"<dir>/app/auth/auth.module"' has no exported member 'SigninComponent'.

即使出口了重要的零部件.

项目文件夹 struct 如下所示:

app/auth/auth.module.ts:

import { NgModule }       from '@angular/core';
import { CommonModule }   from '@angular/common';
import { FormsModule }    from '@angular/forms';

import { RegisterComponent }    from './components/register.component';
import { SigninComponent }    from './components/signin.component';
import { HomeComponent }    from './components/home.component';

import { AuthService } from './services/auth.service';
import { AuthHttp } from './services/auth-http';

@NgModule({
  imports: [
      CommonModule,
      FormsModule
  ],
  declarations: [
      RegisterComponent,
      SigninComponent,
      HomeComponent
  ],
  providers: [
      AuthService,
      AuthHttp
  ],
  exports: [
      RegisterComponent,
      SigninComponent,
      HomeComponent
  ]
})
export class AuthModule {}

app/auth/components/signin.component.ts:

import { Component } from '@angular/core';
import { Router } from '@angular/router';
import { AuthService } from '../services/auth.service';

@Component({
    selector: 'signin',
    templateUrl: 'app/auth/signin.html'
})
export class SigninComponent {
    ...
}

app/app.component.ts:

import { Component, OnInit } from '@angular/core';
import { Router, RouterOutlet } from '@angular/router';
import { SigninComponent, RegisterComponent } from './auth/auth.module';
import { AuthHttp } from './auth/services/auth-http';
import { AuthService } from './auth/services/auth.service';

@Component({
    selector: 'myapp',
    templateUrl: 'app/app.html'
})

export class AppComponent implements OnInit {
    ...
}

app/app.module.ts:

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule }   from '@angular/forms';
import { HttpModule }    from '@angular/http';
import { RouterModule } from '@angular/router';
import { AppRoutingModule } from './app-routing.module';
import { AuthModule } from './auth/auth.module';

import { AppComponent } from './app.component';

import { AuthService } from './auth/services/auth.service';
import { AuthHttp } from './auth/services/auth-http';

@NgModule({
  declarations: [
      AppComponent,
      AuthService,
      AuthHttp
  ],
  bootstrap: [ AppComponent ],
  imports : [
      BrowserModule,
      FormsModule,
      HttpModule,
      AuthModule,
      AppRoutingModule
  ],
  providers: [
      AuthService,
      AuthHttp
  ]
})
export class AppModule {
}