WinSCP.SessionRemoteException:connection unexpectedly closed

[color=green]Imports System
Imports WinSCP

Public Class Form1

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim i As Integer

        i = Upload()

        If i = 0 Then
            Label1.Text &= " Erfolg"
        Else
            Label1.Text &= " Fehlschlag"
        End If
    End Sub

    Public Function Upload() As Integer

        Try
            ' Setup session options
            Dim mySessionOptions As New SessionOptions
            With mySessionOptions
                .Protocol = Protocol.Sftp
                .HostName = "10.7.96.123"
                .UserName = "XXX_XXX"
                .Password = "YYY_YYY"
                ' .GiveUpSecurityAndAcceptAnySshHostKey = True
                ' .GiveUpSecurityAndAcceptAnySshHostKey = True
                .SshHostKeyFingerprint = "ssh-rsa 1024 62:d8:XX:28:ed:cf:9a:65:eb:ba:8d:2f:4b:ad:a5:63"
                .SshPrivateKeyPath = "C:\daten\WinSCPPortable\new\XXX_XXX.ppk"
                ' .FtpMode = FtpMode.Active
            End With


            Using mySession As Session = New Session
                mySession.SessionLogPath = "C:\daten\VB\File_Uploader_2\File Uploader 2\bin\Debug\test.log"
                ' Connect
                mySession.Open(mySessionOptions)

                ' Upload files
                Dim myTransferOptions As New TransferOptions
                myTransferOptions.TransferMode = TransferMode.Binary

                Dim transferResult As TransferOperationResult
                transferResult = mySession.PutFiles("c:\test\Hund\test.txt", "/upload/", False, myTransferOptions)

                ' Throw on any error
                transferResult.Check()

                ' Print results
                For Each transfer In transferResult.Transfers
                    Label3.Text &= " Upload of" & transfer.FileName & " succeeded"
                Next
            End Using

            Return 0
        Catch e As Exception
            Label3.Text &= " " & e.ToString
            Return 1
        End Try

    End Function

End Class[/color]