Javascript ошибка BX is not defined

<?php
require_once($_SERVER['DOCUMENT_ROOT'].'/bitrix/modules/main/include/prolog_before.php');
$APPLICATION->ShowHead();
CJSCore::Init(array("fx"));
?>

<sc ript>

        // делаем ajax запрос в компонент my_components:ajax к методу testAction()
        var request = BX.ajax.runComponentAction('custom:testcomponent', 'myTest', {
            mode: 'class',
            data: {
                param1: 'my_param1_value',
                param2: 'my_param2_value',
                param3: 'developer',
                sessid: BX.message('bitrix_sessid')
            }
        });

        // промис в который прийдет ответ
        request.then(function (response) {
            console.log(response);
        });

</sc ript>

<?require_once($_SERVER['DOCUMENT_ROOT'].'/bitrix/modules/main/include/epilog_after.php');?>

Uncaught (in promise)
Push & Pull server is disabled