php - How to make routes in group correctly? (CodeIgniter 4)

one text

I have a routes group like this. When i tried to run 'detail_datapegawai' page, it said "404 - File Not FoundController is not found".

this is my routes code:

$routes->group('admin', function ($routes) {

    $routes->add('admin', 'Admin\datapegawai::datapegawai');
    $routes->add('admin/(:segment)', 'Admin\datapegawai::detail_pegawai/$1');
});

my controller folder is 'Admin' and the file name is 'Datapegawai.php' while the file views name is 'detail_datapegawai.php'

this routes $routes->add('admin', 'Admin\datapegawai::datapegawai'); works perfectly. while this one $routes->add('admin/(:segment)', 'Admin\datapegawai::detail_pegawai/$1'); have an 404 error as i said before.

controller:

    public function detail_pegawai($slug)
    {

        $data = [
            'title' => 'Admin | Detail Pegawai',
            'profilpegawai' => $this->profilpegawaiModel->getProfilpegawai($slug)
        ];

        return view('user_admin/detail_datapegawai', $data);
    }

button detail to go to 'detail_datapegawai' page:

<a href="/admin/<?= $profil['slug']; ?>" class="btn btn-sm btn-primary">
   <i class="fa fa-sm fa-eye" style="color: white;"></i>
</a>

hope you guys can understand what i said, please help if you can. thankyou so much.