Merge References

That's all I have done and working, but if I want all the elements to be moved to a new empty blank project, I am an error, that the elements do not exist, how to be?

 private void MergeRefernces(object sender, EventArgs e)
        {

            micro = new MicroStationDGN.Application();

           designFile = micro.ActiveDesignFile;

            MicroStationDGN.ElementScanCriteria scan = new MicroStationDGN.ElementScanCriteria();
            scan.IncludeOnlyVisible();
                MicroStationDGN.ElementEnumerator enumer =micro.ActiveDesignFile.DefaultModelReference.Attachments[1].Scan(scan);
                while (enumer.MoveNext())
                {
                    designFile.Models[1].Activate();
                    MicroStationDGN._Element sourceElem = enumer.Current;
                    designFile.DefaultModelReference.AddElement(sourceElem);                       
                }
                designFile.Views[1].Redraw();
                designFile.DefaultModelReference.Attachments.Remove(1);
           
        }