Wordpress如何在动作钩子中使用过滤器？

Question

尝试在woocommerce add_action挂钩中调用add_filter时遇到问题。当用户第一次注册时，我必须添加自定义费用，如果他已经登录并升级其会员资格，那么我想删除这些费用。过滤器正在运行，但它会删除第一次注册以及升级的费用。我在结帐页面上调用它，但它不起作用。这是我的代码。

function my_remove_signup_fee( $subscription_sign_up_fee, $product ) {
    $subscription_sign_up_fee =0;
    return $subscription_sign_up_fee;
}    

add_action('woocommerce_cart_totals_after_billing', 'action_cart_calculate_totals');     
function action_cart_calculate_totals( $cart_object ) {
    //echo "<pre>";
    //print_r($cart_object);

    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    if ( !WC()->cart->is_empty() ):
        foreach( WC()->cart->get_cart() as $cart_item ){
            $product_id = $cart_item['product_id'];
        }
        $subfeeArr = get_post_meta( $product_id,'_subscription_sign_up_fee');
        if(!empty($subfeeArr)){
            $subfee = current($subfeeArr);
        }else{
            $subfee =0;
        }
        $current_user = wp_get_current_user();
        $userEmail = $current_user->user_email;
        $mydb = new wpdb('lbmls_c1lbmlsu','qprn230','lbmls_c1lbmls','mysql01.landbrokermls.com');
        $query = "SELECT id FROM users WHERE email = '{$userEmail}' AND com = '1' AND `Coop-Fee` = '1'";
        $rows = $mydb->get_results($query,ARRAY_A);
        if(!empty($rows)){
            $userId = current($rows);
            if($userId!=""){

                return add_filter( 'woocommerce_subscriptions_product_sign_up_fee', 'my_remove_signup_fee', 10, 2 );

            }

        }
    endif;
}