Question about platform geometry detection

[chisato]

I create a dialog image box and assign it to the shape3D, then i add this shap3D under PlatformGeometry. So that the dialog always show over canvas3D.

ViewingPlatform ourView = su.getViewingPlatform();
pg = new PlatformGeometry();
pg.addChild(dialogShape3D);
ourView.setPlatformGeometry(pg);


Then i try to use pickCanvas for detection:

pickcanvas = new PickCanvas(canvas, pg);
pickcanvas.setModePickCanvas.GEOMETRY_INTERSECT_INFO);
pickcanvas.setTolerance(2.0f);      

But when i click the dialog the pickresult got null.

pickcanvas.setShapeLocation(mouseEvent);
PickResult pickresult = pickcanvas.getClosest();

Please advice on above case, thanks ^^