[已解决] Add vertical floating language switcher to website

Hello, I tried following the instructions here to add a vertical floating language switcher to my website https://wpml.org/documentation/getting-started-guide/language-setup/language-switcher-options/custom-language-switcher/

Added this to the functions.php file

add_action('wp_footer', 'wpml_floating_language_switcher');

function wpml_floating_language_switcher() {
echo '';

do_action('wpml_add_language_selector');
echo '';
}

but the language switcher did not appear on my website (mobile or desktop). Not sure what I'm doing wrong.