Example6 doesn't work

Beginner Questions
1

Hi guys.
I’m trying to use navmesh with this project, but don’t know how to combine it.
So I tried examples(6&7) which provided in the package, the newest version 3.5.2. however it doesn’t work.
When I put the “navmesh_example6navmesh” into “Source Mesh” field of NavMeshGraph, the field value goes “None (Mesh)” again, and Debug Log prints this.

Undo: -721361
UnityEngine.Debug:Log(Object)
AstarPathEditor:HandleUndo() (at Assets/AstarPathfindingProject/Editor/AstarPathEditor.cs:2219)
AstarPathEditor:SaveGraphsAndUndo(EventType) (at Assets/AstarPathfindingProject/Editor/AstarPathEditor.cs:2254)
AstarPathEditor:OnSceneGUI() (at Assets/AstarPathfindingProject/Editor/AstarPathEditor.cs:1329)
UnityEditor.DockArea:OnGUI()

I’m using Unity 4.6.20 beta, and project I tried has only AstarPathfindingProject (pro version)
plz help me~

2

Hi

Sorry. This is a consequence of a new version of the Undo system that unity introduced a while ago. It insists on sending an undo event to my scripts when something is drag-and-dropped to an object field. So what happens is that it will be assigned, and then immediately after it will be reverted by an undo event. So far I haven’t found any way to differentiate between the real undo events and that event.
You can work around it by clicking on it to open the object selector.