我正在为页面创建一个Facebook Webhook。当用户向页面发送消息时，它很有效，webhook的结果作为json对象返回：
{"entry": [{"changes": [{"field": "conversations", "value": {"thread_id": "t_100015009722515", "page_id": 1863367573935021, "thread_key": "t_100015009722515"}}], "id": "1863367573935021", "time": 1510797239}], "object": "page"}
但是当登录页面的Facebook Messager并回复用户时，webhook不起作用？
-webhook-page：all subscribed
- 许可：messages, messaging_postbacks, messaging_optins, message_deliveries, message_reads, messaging_payments, messaging_pre_checkouts, messaging_checkout_updates, messaging_account_linking, messaging_referrals, message_echoes, standby, messaging_handovers, messaging_policy_enforcement, conversations, affiliation, attire, awards, bio, birthday, category, checkins, company_overview, culinary_team, current_location, website, videos, ratings, public_transit, products, product_review, price_range, picture, phone, personal_interests, personal_info, payment_options, parking, name, mission, merchant_review, mention, members, location, live_videos, leadgen, hours, hometown, general_manager, general_info, founded, feed, email, description