微信小程序调用企业付款时报错（nodejs搭建后台）

我用nodejs搭建的后台，在调用微信企业付款时报“xml解析错误”，求大神解决啊！

请求参数：
<xml>
<mch_appid>xxxxxxxx</mch_appid>
<desc>提现</desc>
<mchid>xxxxxxxxxxxxx</mchid>
<openid>xxxxxxxxxxxxxx</openid>
<partner_trade_no>LCVRM74N1557636034118</partner_trade_no>
<spbill_create_ip>127.0.0.1</spbill_create_ip>
<amount>1</amount>
<check_name>NO_CHECK</check_name>
<re_user_name>xxx</re_user_name>
<sign>C7C01FC16EE94CE2A416A4C939953834</sign>
</xml>
请求：options = {

    url: 'https://api.mch.weixin.qq.com/mmpaymkttransfers/promotion/transfers',
    method: "POST",
    json: true,
    headers: {
        "content-type": "application/json;charset=utf-8"
    },
    body: formData,
    key: fs.readFileSync('../server/common/file/wxpay/apiclient_key.pem'), //将微信生成的证书放入 cert目录下
    cert: fs.readFileSync('../server/common/file/wxpay/apiclient_cert.pem')
};

返回结果：
return_code: [ 'SUCCESS' ],
return_msg: [ 'XML解析错误' ],
result_code: [ 'FAIL' ],
err_code: [ 'XML_ERROR' ],
err_code_des: [ 'XML解析错误' ]

求大神解决啊！