Laravel 5 Redirecting to login page after authentication instead of Dashborad

I have this problem, my application should redirect users to admin area whose routes are protected (have middle auth). When I login it redirects to login page again but when place the dashboard route outside the route group, it behaves well. What may be the problem? This is my code:

//Code for protected route (does not work) after login

Route::group(['middleware'=>'auth'], function(){
    Route::get('backend/dashboard', array('as'=>'dashboard', 'uses'=>'BackendDashboardController@getDashboard'));
});

//Code for dashboard route placed outside the route group (Works well after login)

Route::get('backend/dashboard', array('as'=>'dashboard', 'uses'=>'BackendDashboardController@getDashboard'));

//Auth controller - Post login function

protected function postLogin() {
        $request = Input::all();
        $user = array(
            'email' => $request['email'],
            'password' => $request['password']
        );
        if ($this->auth->attempt($user)) {
            return redirect(route('dashboard'));

        }else{
            return redirect(route('login'));
        }
    }

I really want to protect my admin routes and place all of them under auth middleware. Kindly avice

via Chebli Mohamed