获取使用HTTP代理时不支持请求的FTP命令

Question

我已经好几天了。 GetRequestStream（）每次都会失败，即使设置并验证为null也是如此。这是奇怪的事情，它只发生在5台机器中的3台，我找不到有什么区别。有人有线索吗？

Public Sub UploadFtpFile_Simple(PushFileName As String)
    Me.CreateFile(PushFileName, Me.FetchData())

    Dim CompleteFTPPath As String = "ftp://ftp.site.com/Filename.csv"
    Dim CompleteLocalPath As String = PushFileName
    Dim UName As String = Site1UserName
    Dim PWD As String = Site1Pass

    Dim reqObj As FtpWebRequest = DirectCast(WebRequest.Create(CompleteFTPPath), FtpWebRequest)
    'reqObj.Proxy = GlobalProxySelection.GetEmptyWebProxy()
    'reqObj.Proxy = Nothing
    'reqObj.Proxy = WebRequest.DefaultWebProxy
    'reqObj.Proxy = New System.Net.WebProxy()
    reqObj.Method = WebRequestMethods.Ftp.UploadFile
    reqObj.Credentials = New NetworkCredential(UName, PWD)
    Dim streamObj As FileStream = File.OpenRead(CompleteLocalPath)
    Dim buffer(streamObj.Length) As Byte
    streamObj.Read(buffer, 0, buffer.Length)
    streamObj.Close()
    streamObj = Nothing
    Try
        If DEBUGMODE Then
            reqObj.GetRequestStream()
        Else
            reqObj.GetRequestStream().Write(buffer, 0, buffer.Length)
        End If
        Console.WriteLine("GetRequestStream Success")
    Catch ex As Exception
        Console.WriteLine("GetRequestStream failure - {0} Stack Track:{1}", ex.Message, ex.StackTrace)
    End Try

    reqObj = Nothing
End Sub