diff --git a/Service/ServiceUtils/History/HistoryCreator.cs b/Service/ServiceUtils/History/HistoryCreator.cs
index d4892d027..d7633f4b6 100644
--- a/Service/ServiceUtils/History/HistoryCreator.cs
+++ b/Service/ServiceUtils/History/HistoryCreator.cs
@@ -73,7 +73,21 @@ namespace BeWo.ServiceUtils.History
 					}
 				}
 			}
+
 			CreateAbsenceTimeHistoryEntry(originalEmployee.AbsenceTimes, newEmployee.AbsenceTimes);
+
+			if (newEmployee.Overtimes != null)
+			{
+				foreach (var item in newEmployee.Overtimes)
+				{
+					if (!item.EmployeeOid.HasValue)
+					{
+						item.EmployeeOid = originalEmployee.Oid.Value;
+					}
+				}
+			}
+
+			
 			CreateOvertimeHistoryEntry(originalEmployee.Overtimes, newEmployee.Overtimes);
 
 
@@ -482,7 +496,7 @@ namespace BeWo.ServiceUtils.History
 					//CostBearer2SupportConcept_ServiceRecords = originalC2S.ServiceRecords,
 					CostBearer2SupportConcept_Status = originalC2S.Status,
 					//CostBearer2SupportConcept_SupportConceptApprovalPeriodList = originalC2S.ApprovalPeriodList
-					CostBearer2SupportConcept_SupportConceptHistoryOid = lOriginal.Oid.Value,
+					CostBearer2SupportConcept_SupportConceptHistoryOid = lOriginal?.Oid,
 					ChangeType = statementType,
 					Notice = originalC2S.Notice
 				};
@@ -502,14 +516,14 @@ namespace BeWo.ServiceUtils.History
 						SupportConceptApprovalPeriod_BudgetOid = item.Budget?.Oid.Value,
 						SupportConceptApprovalPeriod_ContactCountInterval = item.ContactCountInterval,
 						SupportConceptApprovalPeriod_ContactCountPerInterval = item.ContactCountPerInterval,
-						SupportConceptApprovalPeriod_CostBearer2SupportConceptHistoryOid = originalC2S.Oid.Value,
+						SupportConceptApprovalPeriod_CostBearer2SupportConceptHistoryOid = originalC2S?.Oid,
 						SupportConceptApprovalPeriod_EndDate = item.EndDate,
 						SupportConceptApprovalPeriod_IsApprovedBEShifting = item.IsApprovedBEShifting,
 						SupportConceptApprovalPeriod_IsApprovedFixedAmountShifting = item.IsApprovedFixedAmountShifting,
 						SupportConceptApprovalPeriod_MonthlyPayment = item.MonthlyPayment,
 						SupportConceptApprovalPeriod_StartDate = item.StartDate,
 						SupportConceptApprovalPeriod_SupportConceptApprovalPeriod2Employee = item.SupportConceptApprovalPeriod2Employee,
-						SupportConceptApprovalPeriod_SupportConceptHistoryOid = supportConceptHistoryEntry.Oid.Value,
+						SupportConceptApprovalPeriod_SupportConceptHistoryOid = supportConceptHistoryEntry?.Oid,
 						Notice = item.Notice
 					};
 					DAOFactory.GenericDAO.Insert(scApprovalPeriodHistory);