AutoCAD .NET :: How To Overrule On Custom Object

I want to change display of custom object using overrule.

First I made a class implements from polyline.

class BoundaryPolyline : Autodesk.AutoCAD.DatabaseServices.Polyline { }
 
Second I made a polylineJig to draw my custom polyline(BoundaryPolyline).

 public class PolylineJig : EntityJig { public PolylineJig(Point3dCollection p3ds) : base(new BoundaryPolyline()) { ... } ... }

 And then add overrule on BoundaryPolyline to change display of it.

Overrule.AddOverrule(RXObject.GetClass(typeof(BoundaryPolyline)), mydrawOverrule, false);

 But when I loaded dll, fired overrule and redraw. All polyline display were changed.

Then I found that 'RXObject.GetClass(typeof(BoundaryPolyline)' was return 'Polyline' but not 'BoundaryPolyline'.

How to overrule on custom object.