changing listview according to change in treeview and listbox

ListView1.Items.Clear()
Dim a, b As String
a = ListBox1.SelectedItem
If File.Exists(TreeView1.SelectedNode.Text & "\" & a) Then
b = TreeView1.SelectedNode.Text & "\" & a
Dim y As FileInfo = New FileInfo(b)
ListView1.Items.Add(y.Length / 1024 & " KB")
ListView1.Items(0).SubItems.Add(y.CreationTime)
ListView1.Items(0).SubItems.Add(y.LastAccessTime)
ListView1.Items(0).SubItems.Add(y.IsReadOnly)
Else
ListView1.Items.Add("This is a directory")
End If