newly created guard is not working in multiauth laravel routes?

I have created new guard and trying to implement on routes but it is not working but when i try to implement it in controller it works fine. On routes it gives too many redirection error

routes

// Route::group(['middleware' => ['trading_partner']], function () {
Route::group(['prefix' => 'tradingpartners'], function () {
    //contractor auth controller
    Route::get('/login', 'ContractorAuth\ContractorAuthController@getLogin')->name('contractors.login');
    Route::post('/login', 'ContractorAuth\ContractorAuthController@postLogin')->name('contractors.login');
    Route::post('/logout', 'ContractorAuth\ContractorAuthController@postLogout')->name('contractors.logout');
    //user contractor contorller
    Route::get('/dashboard', 'User\ContractorController@contractorDashboard')->name('contractors.dashboard');
    Route::get('/dashboard/pallets_balance_report_table', 'User\ContractorController@palletsBalanceReportTable');
});
// });

controller

class TradingPartnerAuthController extends Controller
{
    use AuthenticatesUsers;

    protected $guardName = 'trading_partner';
    protected $maxAttempts = 3;
    protected $decayMinutes = 2;

    protected $loginRoute;

    public function __construct()
    {
        $this->middleware('guest:trading_partner', ['except' => ['logout', 'postLogout']]);
        $this->loginRoute = route('trading_partners.login');
    }
   }

via Chebli Mohamed