[Papervision3D] Camera Orbit issue

[Dav]

Hi, I was wondering if anyone can help, I've set up my camera to orbit
around an object in the center of the viewport on mouse drag. However when
the camera goes over the top or under the bottom of the object the camera
the view flips.

Here is a copy of my mouse event listeners.

		private function mouseUp(e:MouseEvent):void
		{
			isOrbiting = false;
			stage.removeEventListener(MouseEvent.MOUSE_MOVE,
mouseMove);
		}
		
		private function mouseDown(e:MouseEvent):void
		{
			isOrbiting = true;
			previousMouseX = e.stageX;
			previousMouseY = e.stageY;
			stage.addEventListener(MouseEvent.MOUSE_MOVE,
mouseMove);
		}
		
		private function mouseMove(e:MouseEvent):void
		{
			var differenceX:Number = e.stageX - previousMouseX;
			var differenceY:Number = e.stageY - previousMouseY;
			
			if (isOrbiting)
			{
				cameraPitch += differenceY;
				cameraYaw += differenceX;
				
				cameraPitch %= 360;
				cameraYaw %= 360;
				
				trace("pitch: " + cameraPitch);
				trace("yaw: " + cameraYaw);
				
				//cameraPitch = cameraPitch >= 0 ?
cameraPitch : 0.0001;
				//cameraPitch = cameraPitch <= 180 ?
cameraPitch : 179.9999;
				
				previousMouseX = e.stageX;
				previousMouseY = e.stageY;
				
				camera.orbit(cameraPitch, cameraYaw, true,
cameraTarget);
			}
		}

Thanks!