Fatal error: Uncaught Error: Call to undefined function add_shortcode() in /home/ioscotland/public_html/wp-content/plugins/cornerstone/includes/shortcodes/custom-headline.php:39 Stack trace: #0 {main} thrown in /home/ioscotland/public_html/wp-content/plugins/cornerstone/includes/shortcodes/custom-headline.php on line 39