BlockRef issue

[dsn27]

1. Create BlockRef via code
2. Export project to DXF file
3. Open DXF file again
4. BlockRef is missing

Only line0 will be shown again.

Code to create a BlockRef

GeoObject.Line line0 = GeoObject.Line.Construct();
line0.StartPoint = new GeoPoint(0, 0);
line0.EndPoint = new GeoPoint(100, 0);
cadControl.CadFrame.Project.SetDefaults(line0);
cadControl.CadFrame.Project.GetActiveModel().Add(line0);

GeoObject.Line line1 = GeoObject.Line.Construct();
line1.StartPoint = new GeoPoint(0, 0);
line1.EndPoint = new GeoPoint(100, 100);
cadControl.CadFrame.Project.SetDefaults(line1);

GeoObject.Line line2 = GeoObject.Line.Construct();
line2.StartPoint = new GeoPoint(0, 100);
line2.EndPoint = new GeoPoint(100, 0);
cadControl.CadFrame.Project.SetDefaults(line2);

GeoObject.Block block = GeoObject.Block.Construct();
block.Add(line1);
block.Add(line2);
cadControl.CadFrame.Project.SetDefaults(block);

GeoObject.BlockRef blockRef = GeoObject.BlockRef.Construct(block);
cadControl.CadFrame.Project.SetDefaults(blockRef);

cadControl.CadFrame.Project.GetActiveModel().Add(blockRef);