[away3d] Mouse Over Events on Plane

[kyma]

I'm having some problems with mouse_over events with some planes. The
events seem to fire only a small percentage of the time.

Here is the method in which I'm adding the listeners:

override public function addActivity(activity:Object):void {
                        var activityContainer:ObjectContainer3D = new 
ObjectContainer3D();
                        var activitySprite:ActivitySprite = new
ActivitySprite(markerMaterial,1);
                        activitySprite.mouseEnabled = true;
        
activitySprite.addEventListener(MouseEvent3D.ROLL_OVER,activityHoveredHandler,false,
0,true);
        
activitySprite.addEventListener(MouseEvent3D.MOUSE_DOWN,activityClickedHandler,false,
0,true);
                        activitySprite.setActivityData(activity);
                        activitySprite.z = -300;
                        activitySprite.bothsides = false;
                        activityContainer.rotationY = 
(activity.longitude*-1)+90;
                        activityContainer.rotationX = activity.latitude*-1;
                        activityContainer.addChild(activitySprite);
                        
this.viewComponent.mainContainer.addChild(activityContainer);
                        super.addActivity(activity);
                }

I've tried mouse_over and roll_over, and both are equally
intermittent.

I have two Away view layers stacked to force the z-sorting, but the
planes I'm trying to interact with are on the top layer.  My events
normally fire the first time, but after that, become unreliable,
firing maybe one time in 5-6.
Has anyone seen this before?