反写规则

老师，您好，反写规则中我添加了一个规则，上游单据是采购入库单，下游单据是应付单。字段是我添加的文本字段实物发票号，实物发票开始在采购入库单中是空的，下推到应付单中，手工输入的。反写到采购入库单。保存应付单时报错如下：
{"operation":"AP_Payable.MBIClick.tbSplitSave"}]
发生时间：11:14:07
错误来源： Kingdee.BOS.ServiceHelper
错误信息：Specified cast is not valid.
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调用堆栈：
Server stack trace:
at Kingdee.BOS.Core.Metadata.Util.ConditionParser.VerifyExpression(VerifyExpressionParameter parameter)
at Kingdee.BOS.App.Core.BusinessFlow.WriteBackLogicUnit.ExcessCheckLogic.DoTask()
at Kingdee.BOS.App.Core.BusinessFlow.WriteBackLogicUnit.AbstractBillWritebackLogic.HandleWritebackLogic()
at Kingdee.BOS.App.Core.BusinessFlow.WriteBackEngine.WriteToSourceDataEntity()
at Kingdee.BOS.App.Core.BusinessFlow.WriteBackEngine.Do()
at Kingdee.BOS.App.Core.BusinessFlow.BusinessFlowWriteBack.DoWriteBackEachRule(KeyValuePair`2 rule, WriteBackEngineContext engineContext)
at Kingdee.BOS.App.Core.BusinessFlow.BusinessFlowWriteBack.DoWriteBack(Sheets`1 sheets, AED`1 aed)
at Kingdee.BOS.App.Core.BusinessFlow.BusinessFlowTracker`1.WriteDataToDB(BusinessFlowInstanceCollection newInstances, BusinessFlowTrackerCollection trackerRows, Sheets`1 sheets, Sheets`1 snapshot, AED`1 aed)
at Kingdee.BOS.App.Core.BusinessFlow.BusinessFlowTracker`1.Save(Sheets`1 sheets)
at Kingdee.BOS.App.Core.BusinessFlow.BusinessFlowTrackerApply.Save(DynamicObject[] dataObjects, String operationNumber)
at Kingdee.BOS.App.Core.Save.SaveConvertData(DynamicObject[] dataObject)
at Kingdee.BOS.App.Core.AbstractOprerationService.CallOperation(DynamicObject[]& objs)
at Kingdee.BOS.App.Core.AbstractOprerationService.CallOperatinTransaction(DynamicObject[] objs)
at Kingdee.BOS.App.Core.AbstractOprerationService.DoExcete()
at Kingdee.BOS.App.Core.AbstractOprerationService.Excute(DynamicObject[] dataEntities)
at Kingdee.BOS.App.Core.SaveService.Save(Context ctx, BusinessInfo info, DynamicObject[] dataEntities, OperateOption option, String operationNumber)
Exception rethrown at [0]:
at Kingdee.BOS.ServiceHelper.BusinessDataServiceHelper.Save(Context ctx, BusinessInfo businessInfo, DynamicObject dataObject, OperateOption option, String operationNumber)
at Kingdee.BOS.Model.Bill.BillModel.Save(OperateOption option)
at Kingdee.BOS.Business.Bill.Operation.Save.ExecuteBillOperation(OperateOption option)
at Kingdee.BOS.Core.DynamicForm.AbstractDynamicFormOperation.Operation(CallBackWfAfterOperation callbackwf, IOperationResult result)
at Kingdee.BOS.Core.DynamicForm.AbstractDynamicFormOperation.Execute(InvokeFormOperation4WfParam param, CallBackWfAfterOperation callbackwf)
at Kingdee.BOS.Web.DynamicForm.AbstractDynamicWebFormView.InvokeFormOperation(String operationNumber)
at Kingdee.BOS.Business.DynamicForm.BusinessService.ExcuteOperation.DoAction(FormBusinessServiceArgs e)
at Kingdee.BOS.Core.DynamicForm.FormBusinessServiceUtil.InvokeServices(IDynamicFormView view, Object source, IEnumerable`1 services, Int32 actionType, String activeEntity, DynamicObject activeRow, Int32 rowIndex)
at Kingdee.BOS.Web.DynamicForm.BusinessServiceCaller.InvokeFormBusiness(IDynamicFormView view, Object source, List`1 formBusinessServices, Int32 actionType, String entityKey, Int32 row)
at Kingdee.BOS.Web.DynamicForm.DynamicWebFormView.BarItemClick(String parentKey, String barItemKey, BarDataManager bar, Int32 bartype)
at Kingdee.BOS.Web.DynamicForm.DynamicWebFormView.MainBarItemClick(String barItemKey)
at Kingdee.BOS.Web.DynamicForm.DynamicWebFormController.MainBarItemClick(String itemKey, JSONArray postDatas)
错误数据： System.Collections.ListDictionaryInternal