Strange error with Xmlrpc server

Hi. I need your help. I have several days to try to solve a problem with my code and I do not find the error.
I leave you here what happens to me in case someone could help me.

I'm using Codeigniter 3.1.5 with HMVC and I'm using the xmlrpc libraries. 
I have created two controllers xmlrpc is the part of the server 

PHP Code:

<?php
class Xmlrpc extends MX_Controller {
    
    private $username = '';
    private $pass = '';
    private $id_user;
    
    public function __construct() {
        parent::__construct();
        
        $this->load->library('xmlrpc');
        $this->load->library('xmlrpcs');

        $config['functions']['wp.getCategories'] = array('function' => 'Xmlrpc.getCategories');

        $this->xmlrpcs->initialize($config);

        $this->xmlrpcs->serve();        
    }
    
    public function getCategories($request){
        
        $parameters = $request->output_parameters();

        $this->load->model('publicador/Categorias_model');
        
        $this->Publicador_categorias_model->id_user = 1;
        $categorias = $this->Categorias_model->get_all();
        
        $categories_struct = array();
        foreach ($categorias as $categoria){           
            $struct = array(
                        'categoryId' => array($categoria->id,'int'), 
                        'parentId' => array(0,'int'), 
                        'description' => array($categoria->nombre,'string'), 
                        'categoryDescription' => array($categoria->nombre,'string'), 
                        'categoryName' => array($categoria->nombre,'string'), 
                        'htmlUrl' => array('','string'), 
                        'rssUrl' => array('','string'), 
                    );
            
            $categories_struct[] = array($struct,'struct');
        }
 
        $response = array($categories_struct,'array');

        
        return $this->xmlrpc->send_response($response);
    }

    
    public function index(){
   
        
    }
} 


and xmlrpc_client that I use it to communicate with the server.

PHP Code:

<?php
class Xmlrpc_client extends MX_Controller {
    
    public function __construct() {
        parent::__construct();
    }
    
    public function index(){
        $server_url = base_url().'/index.php/xmlrpc';
        
        $this->load->library('xmlrpc');
        $this->xmlrpc->set_debug(true);
        
        $this->xmlrpc->server($server_url,80);

        $this->xmlrpc->method('wp.getCategories');
        //$this->xmlrpc->method('system.listMethods');
        
        $params = array(
            '1',
            'user',
            'pass',
            array(
                array( 
                    'title' => array('Titulo del articulo','string'),
                    'description' =>array('descripcion del articulo','string'),
                    'categories' => array('Moda')
                ),'struct'
            )
        );

        $this->xmlrpc->request($params);

        if(! $this->xmlrpc->send_request()){
            echo $this->xmlrpc->display_error();
        }else{
            echo '<pre>';
            print_r($this->xmlrpc->display_response());
            echo '</pre>';
        }
    }
} 


In the creation of the server I configure the functions, but when I call them from the client it gives me this error

"Fatal error: Call to undefined method CI :: getCategories () in / home / jbom / public_html / tools / system / libraries / Xmlrpcs. Phpon line 402 "

I think the bug is trying to call CI :: getCategories () instead of Xmlrpc :: getCategories (), but I do not know why this happens.

Thanks.