Nanne Warns Pz

Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($callback) must be a valid callback, function "sslp_get_single_staff_member_stemsoort" not found or invalid function name in /www/doc/www.hgk-koor.nl/www/wp-includes/class-wp-hook.php:324 Stack trace: #0 /www/doc/www.hgk-koor.nl/www/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters('', Array) #1 /www/doc/www.hgk-koor.nl/www/wp-includes/plugin.php(517): WP_Hook->do_action(Array) #2 /www/doc/www.hgk-koor.nl/www/wp-content/plugins/simple-staff-list/public/templates/single-staff-member/staff-meta.php(30): do_action('sslp_single_sta...') #3 /www/doc/www.hgk-koor.nl/www/wp-includes/template.php(812): require('/www/doc/www.hg...') #4 /www/doc/www.hgk-koor.nl/www/wp-content/plugins/simple-staff-list/includes/sslp-core-functions.php(37): load_template('/www/doc/www.hg...', false) #5 /www/doc/www.hgk-koor.nl/www/wp-content/plugins/simple-staff-list/includes/sslp-template-functions.php(89): sslp_get_template_part('single-staff-me...') #6 /www/doc/www.hgk-koor.nl/www/wp-includes/class-wp-hook.php(324): sslp_get_single_staff_member_meta('') #7 /www/doc/www.hgk-koor.nl/www/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array) #8 /www/doc/www.hgk-koor.nl/www/wp-includes/plugin.php(517): WP_Hook->do_action(Array) #9 /www/doc/www.hgk-koor.nl/www/wp-content/plugins/simple-staff-list/public/templates/content-staff-member.php(34): do_action('sslp_single_sta...') #10 /www/doc/www.hgk-koor.nl/www/wp-includes/template.php(812): require('/www/doc/www.hg...') #11 /www/doc/www.hgk-koor.nl/www/wp-content/plugins/simple-staff-list/includes/sslp-core-functions.php(37): load_template('/www/doc/www.hg...', false) #12 /www/doc/www.hgk-koor.nl/www/wp-content/plugins/simple-staff-list/public/templates/single-staff-member.php(33): sslp_get_template_part('content-staff-m...') #13 /www/doc/www.hgk-koor.nl/www/wp-includes/template-loader.php(106): include('/www/doc/www.hg...') #14 /www/doc/www.hgk-koor.nl/www/wp-blog-header.php(19): require_once('/www/doc/www.hg...') #15 /www/doc/www.hgk-koor.nl/www/index.php(17): require('/www/doc/www.hg...') #16 {main} thrown in /www/doc/www.hgk-koor.nl/www/wp-includes/class-wp-hook.php on line 324