Fatal error: Call to undefined function add_shortcode() 1430

wordpress 4.5.3
http://www.mnerp.com/wp-includes/media.php
出错代码：
Fatal error: Call to undefined function add_shortcode() in D:\web\wp-includes\media.php on line 1430

第1430行代码：
add_shortcode(‘wp_caption’, ‘img_caption_shortcode’);