分账提交到

https://api.mch.weixin.qq.com/secapi/pay/profitsharing

返回System.Net.WebException: 基础连接已经关闭: 连接被意外关闭。
提交参数如下：哪里有问题？
<xml>
<mch_id>1459644502</mch_id>
<nonce_str>82plnk7c5jdbl8e4f</nonce_str>
<sign>017D838C8B6D8429BB381312E609D357AF8F38967DDB9A846244C320C258B918</sign>
<sign_type>HMAC-SHA256</sign_type>
<appid>wx12017585ce3b4d6b</appid>
<transaction_id>4200000733202010173528706762</transaction_id>
<out_order_no>B2010170855097102</out_order_no>
<receivers>[{"type":"PERSONAL_OPENID","account":"osgIQ5ez0JDepZqjcVWL7qmzjLhY","amount":30,"description":"\u7528\u6237\u5206\u8D26"}]</receivers>
</xml>