Il tuo codice era un pò sbagliato, ho risolto tutto tranne
codice:
 Dim W As New IO.StreamWriter(SaveFileDialog.FileName)
Mi dà quest'errore
Overload resolution failed because no accessible 'New' can be called with these arguments:
'Public Sub New(path As String)': Reference to a non-shared member requires an object reference.
'Public Sub New(stream As System.IO.Stream)': Reference to a non-shared member requires an object reference.
Pensavo che aggiungere
codice:
Imports System.IO
risolvesse na nn è così