B4J Question sftp Problem

#Region Project Attributes
    #MainFormWidth: 600
    #MainFormHeight: 600
#End Region

Sub Process_Globals
    Private fx As JFX
    Private MainForm As Form
    Private xui As XUI
    Private Button1 As B4XView
    Dim sftp1 As SFtp
End Sub

Sub AppStart (Form1 As Form, Args() As String)
    MainForm = Form1
    MainForm.RootPane.LoadLayout("Layout1")
    sftp1.Initialize("sftp1", "xxx", "xxxx", "test.com", 2222)
    sftp1.SetKnownHostsStore(File.DirApp, "hosts.txt")
    
    sftp1.GetCurrentPath
    
    MainForm.Show
End Sub

Sub Button1_Click
    'xui.MsgboxAsync("Hello World!", "B4X")
    sftp1.UploadFile(File.DirApp,"1001_1.pdf","/test.pdf")
End Sub

Sub sftp1_CommandCompleted (Command As String, Success As Boolean, ReplyCode As Int, ReplyString As String)
    Log ("command=" & Command)
    Log ("success=" & Success)
    Log ("replyCODE=" & ReplyCode)
    Log ("replystring=" & ReplyString)
    
End Sub


Sub sftp1_PromptYesNo (Message As String)
   Dim res As Int = fx.Msgbox2(MainForm,Message, "", "Yes", "", "No",Null)
   'The next line might be a bit confusing. It is a condition.
   'The value will be True if res equals to DialogResponse.POSITIVE.
   sftp1.SetPromptResult(res = fx.DialogResponse.POSITIVE)
  
   'sftp1.SetPromptResult(True)
End Sub

Sub sftp1_ShowMessage (Message As String)
   fx.Msgbox(MainForm,Message, "")
End Sub

Sub sftp1_UploadProgress (ServerPath As String, TotalUploaded As Long, Total As Long)
    Dim s As String
    s = "Uploaded " & Round(TotalUploaded / 1000) & "KB"
    If Total > 0 Then s = s & " out of " & Round(Total / 1000) & "KB"
    Log(s)
End Sub

Sub sftp1_UploadCompleted (ServerPath As String, Success As Boolean)
    Log(ServerPath & ", Success=" & Success)
    If Success = False Then Log(LastException.Message)
End Sub