getting exception when setting NotesRichTextStyle properties

with vb.net 2005,
 I am trying to load html into a domino richtextitem to send email,
but the following code snippet throws an exception at the line:

rtstyle.PassThruHTML = True

i have tried

rtstyle.PassThruHTML = -1
to no avail...

I cannot change any property of the NotesRichTextStyle object unless the value is an enumerated Domino value...



Try
            Dim doc As NotesDocument = Me.createDocument(SendTo, _
                                                         subject, _
                                                         nAttachments, _
                                                         AttachmentPaths, _
                                                         CopyTo, _
                                                         BlindCopyTo)

            If doc IsNot Nothing Then
                Dim rtItem As NotesRichTextItem = doc.CreateRichTextItem("Body")
                Dim rtstyle As Domino.NotesRichTextStyle
                rtstyle = mSess.CreateRichTextStyle
'*****************
                rtstyle.PassThruHTML = True '----> always throws exception, unless 0,or 255 (-1 fails, also)
'*****************                
                rtItem.AppendStyle(rtstyle)
                rtItem.AppendText(htmlText)
                doc.Send(False)
            End If

        Catch ex As Exception
            MsgBox("ERROR in Dom.senddoc->" & vbCrLf & ex.Message)
        End TryStart Free Trial