[VB6] TreeView e XML con identificatori prefissati da valore numerico

[emmebì]

Ho il seguente codice:

Private Sub LoadTreeViewFromXmlFile(ByVal file_name As String, ByVal trv As TreeView)
    Dim xml_doc As DOMDocument
    
    ' Load the XML file into the DOMDocument.
    Set xml_doc = New DOMDocument
    xml_doc.Load file_name

    ' Add the root node's children to the TreeView.
    TreeView1.Nodes.Clear
    AddChildrenToTreeView trv, Nothing, xml_doc.documentElement
End Sub

Private Sub AddChildrenToTreeView(ByVal trv As TreeView, ByVal treeview_parent As Node, ByVal xml_node As IXMLDOMElement)
    Dim xml_child As IXMLDOMElement
    Dim new_node As Node
    Dim myNodeName As String
    
    On Error Resume Next

    ' Examine each XML child.
    For Each xml_child In xml_node.childNodes
        myNodeName = xml_child.nodeName
        
        MsgBox myNodeName

        ' Add the child to the TreeView.
        ' [...]

    Next xml_child
End Sub

Quando l'XML è fatto così tutto OK:

<Items>
  <Cassetti>
    <man01.manuali_vers_standard.org />
    <RASSEGNA_STAMPA.esempio.ACME />
  </Cassetti>
</Items>

Mentre quando un elemento qualsiasi inizia con un numero:

<Items>
  <Cassetti>
    <man01.manuali_vers_standard.org />
    <22RASSEGNA_STAMPA.esempio.ACME />
  </Cassetti>
</Items>

iniziano i problemi e il comando di MsgBox myNodeName sopra dà solo stringhe nulle. Perchè?