Form action not working

This is the code. When you press the submit button, nothing happens

view:

Code:

<form  method="post" action="<?php echo subSECURE;?>/index.php/User/add" autocomplete="off" enctype="multipart/form-data">
<input type="text" name="username" class="form-control" placeholder="" >
<button type="submit" class="btn btn-primary"><?= lang('Core.Dash.Add') ?></button>
</form>

Routes:

PHP Code:

$routes->post('User/add/(:segment)', 'User::add/$1',['filter' => 'auth']); 


Controllers:

PHP Code:

class User extends BaseController
{
    .... 
    public function add(){

 if ($this->request->getMethod() == 'post') {

 // SET UP RULES
 $rules = [
 'username' => [
                    'rules' => 'required',
                    'errors' => [
 'required' => lang('Core.Auth.Error.required')
                    ]
                ],
 ];

 // VALIDATE RULES
 if (!$this->validate($rules)) {
                // isError
 $data['validation'] = $this->validator;
 } else {

 // isOK
 return redirect()->to(subSECURE .'/users');
 }
 }


 }
    ...