Object reference not set to an instance of an object.

我将销售出库单以继承方式生成一个新的单据，做此单时，都可以正常进行，但在点审核的时候，提示

Object reference not set to an instance of an object.

这个怎么检查问题的原因？
详细错误提示：
发生时间：16:05:11
错误来源： Kingdee.BOS.ServiceHelper
错误信息：Object reference not set to an instance of an object.
===================================================
调用堆栈：
Server stack trace:
at Kingdee.K3.MFG.PLN.App.Core.AppBusinessService.ROWriteDownBusinessService.DataPreparation(IEnumerable`1 currentBills)
at Kingdee.K3.MFG.PLN.App.Core.AppBusinessService.ROWriteDownBusinessService.DoActionBatch(AppBusinessServiceArgs e)
at Kingdee.BOS.App.Core.AbstractOprerationService.ExecuteFormBusinessService(IAppFormBusinessService iBusiness, ExtendedDataEntity[] dataEntities, FormBusinessService service)
at Kingdee.BOS.App.Core.AbstractOprerationService.InvokeFormBusiness(DynamicObject[] objs, Int32 iActionPoint)
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(Object[] ids)
at Kingdee.BOS.App.Core.SetStatusService.SetBillStatus(Context ctx, BusinessInfo businessInfo, List`1 pkEntryIds, List`1 paras, String operationNumber, OperateOption option)
Exception rethrown at [0]:
at Kingdee.BOS.ServiceHelper.BusinessDataServiceHelper.SetBillStatus(Context ctx, BusinessInfo businessInfo, List`1 pkEntryIds, List`1 paras, String operationNumber, OperateOption option)
at Kingdee.BOS.Business.Bill.Operation.AbstractStatusConvert.ExecuteBillOperation(List`1 paras, OperateOption option)
at Kingdee.BOS.Business.Bill.Operation.AbstractStatusConvert.ExecuteStatusConvert(List`1 paras)
at Kingdee.BOS.Business.Bill.Operation.Audit.AuditIdeaPrompt()
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