How to create a message in a defined language?

I'd like to know if it is possible to create a message with a defined language (and not with the current site language)?

I've made a custom function (a callback for a rule), but it doesn't seem to work...

function create_message_with_language($my_user, $my_language, $my_message_type){
$values['type'] = $my_message_type;
$values['user'] = $my_user;
$values += array(
'language' => $my_language,
);
$my_message = entity_create('message', $values);
return array('message_with_language' => $my_message);
}