Upload in helpers folder... Y it doesnt upload?

[eluser]Rubiz'[/eluser]
Hi there, I'll be so much happy when I have no doubts about any futures of code igniter :-)

Well, I have problems, now, with uploading files...
I wrote a helper cause I have several types of upload to do, swf, pdf, ppt, mp3...

In my helpers folder I have:

Code:

<?php  if (!defined('BASEPATH')) exit('No direct script access allowed');

function enviar ($caminho, $ext, $tam, $larg, $alt, $nome_campo)
{
    $config['upload_path'] = $caminho;
    $config['allowed_types'] = $ext;
    $config['max_size']    = $tam;
    $config['max_width']  = $larg;
    $config['max_height']  = $alt;

    $this->load->library('upload', $config);
    
    if ( $this->upload->do_upload($nome_campo) ) return $this->upload->data('file_name');
    else $this->upload->display_errors();
}
?>

in my controller...

Code:

if (!empty($_FILES['thumb_plantas']['name'][0]))
        {
            $tipo = 'plantas';
            
            // upload de img ===============================================================================================================
            $caminhoImg_plantas = 'http://www.villabranca.com.br/imgs/upload/' . $sessao . '/' . $subsessao . '/' . $tipo . '/';
            $caminhoThumb_plantas = 'http://www.villabranca.com.br/imgs/upload/' . $sessao . '/' . $subsessao . '/' . $tipo . '/thumbs/';

            for ($i=0; $i < $countPlantas; $i++)
            {
                $img = $this->helpers->uploading->enviar($caminhoImg_plantas, 'gif|jpg|png', '500', '776', '420', 'img_plantas' . $i);
                $thumb = $this->helpers->uploading->enviar($caminhoThumb_plantas, 'gif|jpg|png', '50', '120', '120', 'thumb_plantas' . $i);
            }

            if ($this->Imovel_model->adicionar($sessao, $nome_sessao, $subsessao, $nome_subsessao, $tipo, $img, $thumb, $legenda))
            {
                $nome_usuario = $this->session->userdata('us');                    
                $status['user'] = $nome_usuario;
                $status['status'] = 'sucesso';
                $this->load->view('status', $status);
            }
            else
            {
                $nome_usuario = $this->session->userdata('us');                    
                $status['user'] = $nome_usuario;
                $status['status'] = 'erro';
                $this->load->view('status', $status);
            }
        }

I set up permissions in all folders properties...
I'm calling the helper right?

Is my logic illogical?
I get a blank page as return...