Invalid work with drupal_set_message on submit child form.

When we use drupal_set_message function inside submit hook with english letters all message appears on next screen. But if we use translation to Cyrillic all message are disappear from $_SESSION variable, nor messages displayed.

function some_form_child( $func_id, $is_edit ) {
  modalframe_child_js();

  print_r( $_SESSION ); // debug information

  $form = array();
  return $form;
}

function some_form_child_submit( $form_id, &$form_state ) {
  drupal_set_message( 'test' ); // work perfect
}
/* result after not translated message
$_SESSION = Array
(
    [node_overview_filter] => Array
        (
        )

    [dblog_overview_filter] => Array
        (
        )

    [user_overview_filter] => Array
        (
        )

    [messages] => Array
        (
            [status] => Array
                (
                    [0] => test
                )

        )

)
*/

function some_form_child_submit( $form_id, &$form_state ) {
  drupal_set_message( t('test') ); // doesn't work
}
/* result after use t()
$_SESSION = Array
(
    [node_overview_filter] => Array
        (
        )

    [dblog_overview_filter] => Array
        (
        )

    [user_overview_filter] => Array
        (
        )

    [messages] => 
)
*/