Laravel Routes 5.6

Question

Gentlemen I’m having trouble setting the wheels and returns me the following error:

protected function methodNotAllowed(array $others)
{
    throw new MethodNotAllowedHttpException($others);
}

I’m doing them this way:

route/web.php

$this->post('cadastrar-sub-categoria', 'CategoriaController@cadastrarSubCategoria')->name('cadastrarSubCategoria');

php controller.

public function cadastrarSubCategoria(){
    return 'OK';
}

Where can I be wrong? I am starting my studies in Aravel 5.6!

Thank you.