diff --git a/B3ClientService/BO/Bill/GradeAndWeight/GradeAndWeight_Detail.cs b/B3ClientService/BO/Bill/GradeAndWeight/GradeAndWeight_Detail.cs
index 759acd7..dff5178 100644
--- a/B3ClientService/BO/Bill/GradeAndWeight/GradeAndWeight_Detail.cs
+++ b/B3ClientService/BO/Bill/GradeAndWeight/GradeAndWeight_Detail.cs
@@ -12,7 +12,7 @@ namespace BWP.B3ClientService.BO
     public int Index { get; set; }
 
     [NonDmoProperty]
-    public long OrderDetail_ID { get; set; }
+    public long? OrderDetail_ID { get; set; }
 
     public DateTime? Date { get; set; }
 
diff --git a/B3ClientService/Rpcs/BillRpc/GradeAndWeightRpc.cs b/B3ClientService/Rpcs/BillRpc/GradeAndWeightRpc.cs
index 5b331af..453a9a7 100644
--- a/B3ClientService/Rpcs/BillRpc/GradeAndWeightRpc.cs
+++ b/B3ClientService/Rpcs/BillRpc/GradeAndWeightRpc.cs
@@ -134,8 +134,8 @@ namespace BWP.B3ClientService.Rpcs.BillRpc
           session.Insert(entity);
         else
           session.Update(entity);
-        if (fillTechnics)
-          AddAlready(session, entity.OrderDetail_ID, entity.Technics);
+        if (fillTechnics && entity.OrderDetail_ID.HasValue)
+          AddAlready(session, entity.OrderDetail_ID.Value, entity.Technics);
         session.Commit();
         return entity.ID;
       }