[Codeigniter] Erreur : "You did not select a file to upload"

Bonjour,

je cherche à upload une image lors de l'envoie d'un formulaire et j'ai toujours la même réponse qui est : "You did not select a file to upload"

Voici mon code en esperant que vous puissiez m'aider car c'est assez urgent :/

ça ce passe sur cette page : http://www.lecollectif.tv/index.php/admin/membres


J'utilise le framework codeigniter
Le formulaire :
Code:

<h2>Gérer les membres</h2>
<?php
if(isset($error)){
    echo $error;
}

    $attributes = array('id' => 'form_membre', 'enctype' => "multipart/form-data", 'method' => "POST");
    echo form_open('admin/do_upload', $attributes);
    ?>
    <label for="nom">Nom</label>
    <input type="text" name="nom" id="nom"/>
    <fieldset class="small">
        <label for="logo_form">Logo</label>
        <?php
    $data = array('class' => 'input-form file',
                  'name'  => 'userfile'
        );
   echo form_upload($data);
   ?>
    </fieldset>
    <fieldset class="small" style="margin-left: 20px;">
        <label for="login">Login</label>
        <input type="text" name="login" id="login"/>
    </fieldset>
    <fieldset class="small" style="margin-left: 20px;">
        <label for="mail">Email</label>
        <input type="text" name="mail" id="mail"/>
    </fieldset>
    <fieldset class="small" style="margin-left: 20px;">
        <label for="site">Site</label>
        <input type="text" name="site" id="site"/>
    </fieldset>

    <fieldset class="small">
        <label for="fb">Facebook</label>
        <input type="text" name="fb" id="fb" />
    </fieldset>
    <fieldset class="small" style="margin-left: 20px;">
        <label for="twitter">Twitter</label>
        <input type="text" name="twitter" id="twitter"/>
    </fieldset>
    <fieldset class="small" style="margin-left: 20px;">
        <label for="google">Google</label>
        <input type="text" name="google" id="google"/>
    </fieldset>
    <fieldset class="small" style="margin-left: 20px;">
        <label for="youtube">Youtube</label>
        <input type="text" name="youtube" id="youtube"/>
    </fieldset>
    <label for="description">Description</label>
    <textarea name="description" id="description"></textarea>
    <input type="hidden" name="posted" value="1"/>
    <input type="submit" value="Ajouter" class="btn_form"/>
</form>

La méthode du controleur :
Code:

function do_upload() {
        $config['upload_path'] = './uploads/';
        $config['allowed_types'] = 'gif|jpg|png';
        $config['max_size'] = '1000';
        $config['max_width'] = '1024';
        $config['max_height'] = '768';

        $this->load->library('upload', $config);

        if (!$this->upload->do_upload()) {
            $error = array('error' => $this->upload->display_errors());
            $this->layout->set_theme('admin');
            $this->layout->view('admin/membres', $error);
        } else {
            $data = array('upload_data' => $this->upload->data());
            $nom = $this->input->post('nom');
            $login = $this->input->post('login');
            $email = $this->input->post('mail');
            $site = $this->input->post('site');
            $fb = $this->input->post('fb');
            $tw = $this->input->post('twitter');
            $google = $this->input->post('google');
            $youtube = $this->input->post('youtube');
            $description = $this->input->post('description');
            $filename = $data['file_name'];
            $mdp_un = uniqid();
            $mdp_deux = substr($mdp_un, 0, 8);
            $mdp = sha1($mdp_deux);
            $data['mdp'] = $mdp_deux;
            $this->production->Ajouter_prod($nom, $login, $filename, $email, $site, $description, $mdp, $fb, $tw, $google, $youtube);
             $this->layout->set_theme('admin');
            $this->load->view('ajout_prod_success', $data);
        }
    }