Another translate problem (Vantage Theme)

Hi,
Sorry for my english.
I’ve made vantage-child theme, made .po and .mo files transleted text and uploaded to languages folder child-theme folder (vantage-child).
But my “Posted on” and “by” does not change. Still in english.
Some interesting thing that “Seach” in Main menu is translated.
Something is wrong.
mysite: http://optimumcarcare.pl/detailing/projekty/
my functions.php child theme

<?php

/**
 * Enqueue the parent theme stylesheet.
 */

add_action( 'wp_enqueue_scripts', 'vantage_parent_style' );
function vantage_parent_style() {
    wp_enqueue_style( 'parent-theme', get_template_directory_uri() . '/style.css' );
}

/**
 * Enqueue the child theme stylesheet.
 */

add_action( 'wp_enqueue_scripts', 'vantage_child_style', 20 );
function vantage_child_style() {
    wp_enqueue_style( 'child-theme', get_stylesheet_uri() );
}

/**
 * Set the child theme text domain.
 */

function vantage_child_set_text_domain(){
load_theme_textdomain( 'vantage', get_stylesheet_directory() . '/languages' );
}
add_action('after_setup_theme', 'vantage_child_set_text_domain', 15);

my style.css child theme

/*
Theme Name: Vantage Child
Author: SiteOrigin
Author URI: http://siteorigin.com/
Theme URI: http://siteorigin.com/theme/vantage
Description: Vantage Child Theme
Version: 1.0.0
Template: vantage
Text Domain: vantage
Domain Path: /languages/
*/

/* =Theme customization starts here
-------------------------------------------------------------- */