Custom admin route not working.

Route::group(['middleware' => ['coaster.admin']], function () {
    Route::prefix('admin')->group(function () {
        // Dashboard
        Route::get('/', [\App\Http\Controllers\DashboardController::class, 'index'])
            ->name('coaster.admin.dashboard');

        // CMS Website
        Route::get('/cms-website', [\App\Http\Controllers\CmsWebsiteController::class, 'index'])
            ->name('coaster.admin.cms-website');
    });

Those are my routes. The first one to the Dashboard works fine, but the cms-website route gives me the error "coaster.admin is not defined"

Any solutions?