mailchimp - Mailchimp api v3 - merge_fields でリストにメンバーを追加する

Question

このオブジェクトを HTTP POST として送信します。

{
    "email_address": "rickard@transticket.se",
    "status": "subscribed",
    "merge_fields": {
        "APA": "1",
        "HEJ": "2"
    }
}

にhttps://us13.api.mailchimp.com/3.0/lists/045dfc0a43/members

そして、私はこの応答を得ました：

{
    "type": "http://developer.mailchimp.com/documentation/mailchimp/guides/error-glossary/",
    "title": "Invalid Resource",
    "status": 400,
    "detail": "The resource submitted could not be validated. For field-specific details, see the 'errors' array.",
    "instance": "",
    "errors": [ {
        "field": "",
        "message": "Schema describes object, array found instead"
    }]
}

何か案は？