Android Question JSch : null object reference

Sub BtsLstFiles_Click
    sftp1.List(EditText1.Text)
    sftp1.GetCurrentPath
End Sub

#Region  Project Attributes
    #ApplicationLabel: PROTIME SMS Alert
    #VersionCode: 1
    #VersionName:
    'SupportedOrientations possible values: unspecified, landscape or portrait.
    #SupportedOrientations: unspecified
    #CanInstallToExternalStorage: False
#End Region

#Region  Activity Attributes
    #FullScreen: False
    #IncludeTitle: True
#End Region

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'These variables can be accessed from all modules.

    Dim sftp1 As SFtp
    Dim database As SQL
    Dim lstSms As List
End Sub

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    'These variables can only be accessed from this module.

    Private BtsLstFiles As Button
    Private ListView1 As ListView
    Private EditText1 As EditText
    Private btnReadCSV As Button
    Private btnFlushData As Button
    Private btnCompare As Button
    Private btnSendSms As Button
End Sub

Sub Activity_Create(FirstTime As Boolean)
    'Do not forget to load the layout file created with the visual designer. For example:

    If FirstTime Then
      
        ' DATABASE
        DB.CreateDatabase
      
        ' SFTP
        sftp1.Initialize("sftp1", "XXXXX_SFTP", "7&", "server.domain.fr", 22)
        sftp1.SetKnownHostsStore(File.DirInternal, "hosts.txt")
      
        'AUTRES
        lstSms.Initialize
      
        End If
      
    Activity.LoadLayout("L1")
End Sub

Sub Activity_Resume
    sftp1.Activity_Resume
End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub

Sub sftp1_PromptYesNo (Message As String)'
    'sftp1.SetPromptResult(True)
    Dim res As Int = Msgbox2(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 = DialogResponse.POSITIVE)
End Sub

Sub sftp1_ShowMessage (Message As String)
    Msgbox(Message, "")
End Sub

Sub BtsLstFiles_Click
    sftp1.List(EditText1.Text)
    sftp1.GetCurrentPath
End Sub

Sub sftp1_CommandCompleted(Command As String, Success As Boolean, Reply As String)
    Log(Success)
    If Success Then
        'ToastMessageShow(Command,False)
        'ToastMessageShow(Reply,False)
        Else
        Log(LastException.Message)
        End If
End Sub

Sub sftp1_ListCompleted (ServerPath As String, Success As Boolean, Folders() As SFtpEntry, Files() As SFtpEntry)
    If Success=True Then
        ToastMessageShow("success !",False)
    Else
        'ToastMessageShow("Error : " & LastException.Message,True)
        Log(LastException.Message)
        End If
End Sub

Sub btnReadCSV_Click
    PTFILES.ReadCsvFile
    DB.UpdateDailyPatterns
End Sub

Sub btnFlushData_Click
    DB.flushdata
End Sub

Sub btnCompare_Click
    DB.CompareDailyPatterns
End Sub

Sub btnSendSms_Click
    DB.GetSmsToSend
End Sub