微信支付-分账场景-添加分账接收方，报错请确保商户号mchId已设置，有什么定位思路吗

【请求地址】：https://api.mch.weixin.qq.com/pay/profitsharingaddreceiver

【请求数据】：<xml>

  <appid>wx229499****976785</appid>

  <mch_id>1523**7871</mch_id>

  <nonce_str>1611281961951</nonce_str>

  <sign>557C19108ED53BE907482FAF9977265D122A363A086830210A39AB1BB9925978</sign>

  <sign_type>HMAC-SHA256</sign_type>

  <receiver>[{&quot;type&quot;:&quot;PERSONAL_OPENID&quot;,&quot;account&quot;:&quot;o_Oq55ZNPcXWxu0MXkb2Vnmti7_I&quot;,&quot;relationType&quot;:&quot;USER&quot;}]</receiver>

</xml>

【异常信息】：请确保商户号mchId已设置