Membership Checkout

Fatal error: Uncaught Error: Call to undefined function get_level_hours() in /www/htdocs/w018d689/train-express-languages.de/wp-content/themes/masterstudy-child/paid-memberships-pro/pages/checkout.php:82 Stack trace: #0 /www/htdocs/w018d689/train-express-languages.de/wp-content/plugins/paid-memberships-pro/includes/functions.php(384): include() #1 /www/htdocs/w018d689/train-express-languages.de/wp-content/plugins/paid-memberships-pro/includes/init.php(85): pmpro_loadTemplate('checkout', 'local', 'pages') #2 /www/htdocs/w018d689/train-express-languages.de/wp-includes/shortcodes.php(433): pmpro_pages_shortcode('', '', 'pmpro_checkout') #3 [internal function]: do_shortcode_tag(Array) #4 /www/htdocs/w018d689/train-express-languages.de/wp-includes/shortcodes.php(273): preg_replace_callback('/\\[(\\[?)(pmpro_...', 'do_shortcode_ta...', '[pmpro_checkout...') #5 /www/htdocs/w018d689/train-express-languages.de/wp-includes/class-wp-hook.php(324): do_shortcode('[pmpro_checkout...') #6 /www/htdocs/w018d689/train-express-languages.de/ in /www/htdocs/w018d689/train-express-languages.de/wp-content/themes/masterstudy-child/paid-memberships-pro/pages/checkout.php on line 82