Reply to response using Facebook API

Question

I am using the Facebook API in my project. If I want to create a user response to a top-level comment, I use this request for fb api:

POST /{parent_comment_id}/comments?message={message}

and everything is in order.

But when I tried to answer another answer, I have this error

code: 1705, message: (#1705) There was an error posting to this wall [HTTP 400]

How do I send my request to fb if I want to answer another answer?