treeview 中节点伸展或收缩后，节点的图像如何随着改变？

Notes.Add(relative, relationship, key, text, image, selectedimage)
Image:在关联的 ImageList 控件中的图像的索引

我有一个例子,你看看

Set MyNod = TreeView1.Nodes.add(, , "M_", "全部", "close")
MyNod.Image = "close": MyNod.ExpandedImage = "open"

[此贴子已经被作者于2007-4-30 13:36:10编辑过]

Set nodX = TreeView1.Nodes.Add(, , "root1", "水准测量", "pic1", "pic2")

Set nodX = TreeView1.Nodes.Add("root1", tvwChild, "root1_1", "闭合水准路线", "pic1", "pic2")
Set nodX = TreeView1.Nodes.Add("root1", tvwChild, "root1_2", "附合水准路线", "pic1", "pic2")
Set nodX = TreeView1.Nodes.Add("root1", tvwChild, "root1_3", "支水准路线", "pic1", "pic2")
Set nodX = TreeView1.Nodes.Add("root1", tvwChild, "root1_4", "水准网（严密）", "pic1", "pic2")

nodX.Image = "pic1"
nodX.ExpandedImage = "pic2"
还是不行，两个pic1和pic2不能来回切换，为什么？

各位高人看看把，问题应该不难！