SelectedNodeChanged Event Not Fired for TreeView

[asn1981]

I have a .Net 2.0 treeview control on my ASP.net website.
the issue i have is that when a dynamically created treenode has been created and then is clicked..
the page is not posted back and the SelectedNodeChanged event does not get fired.
below i have shown my code that created the treenode
i have tried setting the TreeNode SelectAction as both select and selectAction neither of which makes any difference is firing the SelectedNodeChanged event.

Private Sub DotvNavigation()
        'build the tvNavigation

        tvNavigation.Nodes.Clear()
        Dim RootTreeNode As New TreeNode
        RootTreeNode.Text = "System Name"
        tvNavigation.Nodes.Add(RootTreeNode)

        datareader = GetSqlData.GetNodes4Navigation
        While datareader.Read
            If datareader.HasRows = True Then
                Dim iCount As Integer
                Dim iParentMenuID As Integer = datareader(0)
                Dim sMenuItemName As String = datareader(1)
                Dim iMenuID As Integer = datareader(2)

                Dim TreeNode As New TreeNode
                TreeNode.Text = sMenuItemName
                TreeNode.Value = iMenuID


                'TreeNode.SelectAction = TreeNodeSelectAction.Select
                TreeNode.SelectAction = TreeNodeSelectAction.SelectExpand

                RootTreeNode.ChildNodes.Add(TreeNode)
               
        End While

    End Sub

[asn1981]

any1 any ideas?