Help NullReferenceException was unhandled when coding with treeview

I am new to vb.net 2005 and am desperate in need of solution as I faced error on the following codes.

Public Class Form1
Private PreviousTab As TabControl
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Me.Load
ListNodes(TreeView1.Nodes(0))
With TreeView1.Nodes.Item("AdminMenu")
.Nodes.Item("AddCustomer").Tag = TabAddCust
.Nodes.Item("DeleteCust").Tag = TabDeleteCust
End With
End Sub
Private Sub ListNodes(ByVal StartNode As TreeNode)
Debug.WriteLine(StartNode.Name)
For Each n As TreeNode In StartNode.Nodes
ListNodes(n)
Next
End Sub

Private Sub TreeView1_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterSelect
If PreviousTab IsNot Nothing Then
PreviousTab.Visible = False
End If
If e.Node.Tag IsNot Nothing Then
Dim ActiveTab As TabControl = CType(e.Node.Tag, TabControl)
ActiveTab.Visible = True
ActiveTab.Dock = DockStyle.Fill
PreviousTab = ActiveTab
End If
End Sub

When I run the program two lines of the code face error message of NullReferenceException was unhandled.

.Nodes.Item("AddCustomer").Tag = TabAddCust :confused:
.Nodes.Item("DeleteCust").Tag = TabDeleteCust :confused:

I am clueless on how to solve this.

Please help me!!!

You need to verify that TreeView1 contains a node with the key "AdminMenu" that in turn holds two nodes with the keys "AddCustomer" and "DeleteCust".

Furthermore, you should post all your VB.Net questions in the VB.Net forum, a moderator will probably move this thread as soon as possible.
And you should wrap your code in [HIGHLIGHT=VB.Net][/HIGHLIGHT] tags.

This is the Feedback forum and you need to post that in VB.net.

Thread Moved

Thanks for the answer.

Could you give me some tips on how to verify the nodes given the Admin Menu node as the root node and the child node is AddCustomer? I need sample coding to understand because I just started learning visual basic.net less than a month.

So sorry for using the wrong forum I think being awake for too long figuring out solution makes me blur :blush: .

please help me, i have big problem in my solutions projects in visual studio 2005

System.NullReferenceException was unhandled
Message="Object reference not set to an instance of an object."
Source="MBSControls"
StackTrace:
at MBSControls.ListViewXTC.InitializeList(Object items) in C:\Projects\TimeSheet\MBSControls\ListViewXTC.cs:line 208