Laravel Dingo API always response "Not Found"

Question

here's my code:

// api.php
$api = app('Dingo\Api\Routing\Router');
$api->version('v1', function ($api) {
        $api->get('test', function (Request $request) {
            return "test";
        });
}

// request
http://localhost:8000/api/test

i didn't set API_PREFIX.

and all of my dingo Route is not working.

please help.