应收单WEBAPI保存报错

根据客户的需求，在平台对接方面需要调用应收单的WEBAPI保存接口，之前保存是没有问题的，打过四月份的最新补丁后，传入json老是报这一错误，请大神们帮忙看看是什么问题，json如下：
{
"Creator": "kingdee",
"NeedUpDateFields": [

],
"Model": {
"FID": 0,
"FBillTypeID": {
"FNumber": "YSD01_SYS"
},
"FCUSTOMERID": {
"FNumber": "CUST0008"
},
"FPAYORGID": {
"FNumber": "8001"
},
"FSETTLEORGID": {
"FNumber": "8001"
},
"FDATE": "2017-3-06 12: 00: 00",
"FISTAX": "true",
"FCURRENCYID": {
"FNumber": "PRE001"
},
"FEntityDetail": [
{
"FSeq": 0,
"FMaterialId": {
"FNumber": "02.02.P0383204"
},
"FTaxPrice": "178",
"FPriceQty": "10",
"FSourceBillNo": "XSCKD000238",
"FSOURCETYPE": "SAL_OUTSTOCK",
"FEntityDetail__FEntityDetail_Link": [
{
"FEntityDetail_Link_FRuleId": "AR_OutStockToReceivableMap",
"FEntityDetail_Link_FSTableName": "T_SAL_OUTSTOCKENTRY",
"FEntityDetail_Link_FSBillId": 100333,
"FEntityDetail_Link_FSId": 108824
}
]
}
]
}
}
报错：
{"FieldName":"未将对象引用设置到对象的实例。","Message":" 在 Kingdee.K3.FIN.AR.Business.PlugIn.ReceivableEdit.SetAccountType(Boolean IsNew)\r\n 在 Kingdee.BOS.Core.DynamicForm.PlugIn.DynamicFormModelPlugInProxy.FireAfterCreateNewData(EventArgs e)\r\n 在 Kingdee.BOS.Core.DynamicForm.AbstractDynamicFormModel.CreateNewData(DynamicObject newObject)\r\n 在 Kingdee.BOS.Model.Bill.BillModel.CreateNewData(DynamicObject newObject)\r\n 在 Kingdee.BOS.WebApi.FormService.Save.Revole()\r\n 在 Kingdee.BOS.WebApi.FormService.Save.Execute()\r\n 在 Kingdee.BOS.WebApi.FormService.BillOperationService.ExecuteOperation(FormOperation op, String data)","DIndex":0}