Livedoor Blogで Windows Live Writer が 使えない理由

Dim res, b64, wsse, tim, non, apiurl, username, password As String
Dim webreq As System.Net.HttpWebRequest
Dim webres As System.Net.HttpWebResponse
Dim shasp As New System.Security.Cryptography.SHA1CryptoServiceProvider()
Dim dtime As DateTime
Dim sis As System.IO.Stream

non = "0123456789ABCDEFGHIJ" ' 適当な２０文字
apiurl = TextBox5.Text
username = TextBox1.Text
password = TextBox2.Text
webreq = CType(System.Net.HttpWebRequest.Create(apiurl), System.Net.HttpWebRequest)
webreq.Method = "GET"
webreq.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"
dtime = DateTime.Now
tim = dtime.ToString("yyyy-MM-ddTHH:mm:ssZ")

If CheckBox1.Checked Then '旧認証
    b64 = System.Convert.ToBase64String(shasp.ComputeHash
System.Text.Encoding.UTF8.GetBytes(non & tim & password)))
Else '新認証
    b64 = System.Convert.ToBase64String(shasp.ComputeHash
(System.Text.Encoding.UTF8.GetBytes(System.Convert.ToBase64String
(System.Text.Encoding.ASCII.GetBytes(non)) & tim & password)))
End If
wsse = "UsernameToken Username=""" & username & """, PasswordDigest="""
& b64 & """, Created=""" & tim & """, Nonce=""" & System.Convert.ToBase64String
(System.Text.Encoding.ASCII.GetBytes(non)) & """"
webreq.Headers.Add("X-WSSE", wsse)
webreq.Proxy = System.Net.WebProxy.GetDefaultProxy()
webreq.Timeout = 5000000

TextBox3.Text = webreq.Headers.ToString()
Try
   webres = Nothing
   sis = webreq.GetResponse().GetResponseStream()
   Dim sres As New System.IO.StreamReader(sis, System.Text.Encoding.GetEncoding
 ("UTF-8"))
   res = sres.ReadToEnd()
   TextBox4.Text = res
Catch exc As System.Net.WebException
   If exc.Status = System.Net.WebExceptionStatus.ProtocolError Then
      webres = CType(exc.Response, System.Net.HttpWebResponse)
      TextBox4.Text = webres.StatusCode & ":" & webres.StatusDescription
   Else
      TextBox4.Text = exc.Message
   End If
Finally
End Try