Error notice

Hello,

in my template.php I use a hook for replace the field files with Plupload form in my node form :

function MyTheme_form_folder_node_form_alter(&$form, &$form_state) {
$form['field_files'] = array(
  '#type' => 'plupload',
  '#title' => t('Upload files'),
  '#description' => t('This multi-upload widget uses Plupload library.'),
);
}

But if I upload files and save the node, files aren't saved in site and I get this error :

Notice : Undefined index: #language in locale_field_entity_form_submit() (line 438 in /home/www/mysite.com/modules/locale/locale.module).

I made ​​a mistake? The hook code is not good?

Thanks for your help.