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Hi,
I try to create a new contact but I get an error (please see the attachment) 

This is my code:

Public Function POST_Contact_FullInfo(ByVal XMLData As String) As String
 Dim sPassword As String = My.Settings.API_password
        Dim sUsername As String = My.Settings.API_username
        Dim sAPIKey As String = My.Settings.API_Key
        Dim sUri As String = "https://api.constantcontact.com/ws/customers/" & sUsername & str_Contact_uri
      
        'setup httpWebReqeust to send the data

        Dim theLoginCredentials As CredentialCache = New CredentialCache()
      
        theLoginCredentials.Add(New Uri(sUri), "Basic", New NetworkCredential((sAPIKey & "%" & sUsername), sPassword))

        Dim address As New Uri(sUri)

        Dim theRequest As HttpWebRequest = TryCast(WebRequest.Create(address), HttpWebRequest)
        theRequest.Credentials = theLoginCredentials
        theRequest.Method = WebRequestMethods.Http.Post '"POST" '
        theRequest.ContentType = "application/atom+xml"
        theRequest.PreAuthenticate = True
''' I used the same credentials for getting data and they are ok.

        Dim byteArray As Byte() = Encoding.ASCII.GetBytes(XMLData)

        Dim XMLResponse As String = "" '= "Bytes to send: " + byteArray.Length
        Try
            theRequest.ContentLength = byteArray.Length

            '// Create a stream for the POST Request
            Dim streamRequest As Stream = theRequest.GetRequestStream()
            streamRequest.Write(byteArray, 0, byteArray.Length)
            'streamRequest.Close()
            Dim reqResponse As HttpWebResponse
            reqResponse = TryCast(theRequest.GetResponse(), HttpWebResponse)
           
            Dim reader As New StreamReader(reqResponse.GetResponseStream())

            XMLResponse = reader.ReadToEnd()

            '// Close Reader
            reader.Close()

            ' End Using

            '// Close the response to free up the system resources
            'Response.Close()
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
Please help me with this.
Thanks!
Halford13