Can't bind to 'ngModel' since it isn't a known property of 'input'.

Galera, estou tomando este erro : Can't bind to 'ngModel' since it isn't a known property of 'input'. Porém eu já importei o FormsModule, conforme mostrado nas video-aulas. Alguem sabe pq este erro persiste?

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import { HttpModule } from '@angular/http';
import { PrincipalComponent } from './principal/principal.component';
import { routing } from './app.routes';
import { HomeComponent } from './home/home.component';
import { UsuarioComponent } from './usuarios/usuario.component';
import { AuthManager } from './authManager';
import { AuthService } from './auth.service';
import 'rxjs/add/operator/map';
import { BotaoModule } from './botao/botao.module';
import { FiltroPorNome } from './usuarios/usuario.pipes';
import { CadastroUserModule } from './cadastroUser/cadastroUser.module';
import { FormsModule } from '@angular/forms';



@NgModule({
    providers: [ AuthManager, AuthService ],
    imports: [ BrowserModule, HttpModule, routing, BotaoModule, CadastroUserModule, FormsModule ],
    declarations: [ AppComponent, PrincipalComponent, HomeComponent, UsuarioComponent, FiltroPorNome ],
    bootstrap: [ AppComponent ]
})
export class AppModule { }