It's all in how the object is created. Whoever creates the object will have its "tno.isMine" evaluate to "true".
You need to create objects using TNManager.Create. If you just use GameObject.Instantiate, you are making local objects, not networked objects. Likewise if your object is a part of the scene, its owner flag is undefined.
So in short, make sure you create your player avatar using TNManager.Create.