Laravel 5路由管理站点错误

I can't go to the admin part of my site. I'm landing always on the main site. This problem is only with admin, every another routes working perfectly.

Routes:

Route::group(['middleware' => ['web']], function () {
     // Login, logout
     Route::get('admin', array('as' => 'login', 'uses' => 'AuthController@index'));
     Route::post('admin/login', array('as' => 'cms_login', 'uses' => 'AuthController@login', 'before' => 'csrf'));
     Route::get('admin/logout', array('as' => 'logout', 'uses' => 'AuthController@logout'));
}

AuthController:

public function index(){
    // Show login form
    return view('backend/pages/login');
} 

Doesn't matter what I do, I landing always on the home screen www.example.com if I try to call www.example.com/admin.

The problem was the app/http/Middleware/RedirectIfAuthenticated.php

Here was "return redirect('/');" that's why I landed always on the home screen