Read/Write XML trouble with VB2005

Hi,

I need to populate treeview from XML file. I found this code written in VB2003 whitch doesn't work in VB2005. There is an error "InvaliOperationException" in line "Dim treeData As TreeViewData = CType(ser.Deserialize(reader), TreeViewData)"

VB Code:

Public Shared Sub LoadTreeViewData(ByVal treeView As TreeView, ByVal path As String)
        'Create as serializer and get the file to deserialize
        Dim ser As New System.Xml.Serialization.XmlSerializer(GetType(TreeViewData))
        Dim file As New System.IO.FileStream(path, IO.FileMode.Open)
        Dim reader As New System.Xml.XmlTextReader(file)
 
        'Deserialize the file and populate the treeview
        Dim treeData As TreeViewData = CType(ser.Deserialize(reader), TreeViewData)
        treeData.PopulateTree(treeView)
 
        'Tidy up
        reader.Close()
        file.Close()
        file = Nothing
    End Sub

Thanks in advance.