[求助]使用wininet编写FTP上传照片程序，老是上传失败

Private Function PutImg(n As Integer) 'n为要上传的文件数
'上传照片
Dim ftpurl As String
Dim foldes As String
Dim isput As Boolean
Dim i As Integer
i = n - 1
Do While i >= 0
  foldes = "/" & camera & "/" & List3.List(i) & "/" '生成照片上传目标路径，对应相机文件夹，list3用来存放文件夹名称
  Call c.CreatFolde(foldes) '在服务器上新建文件夹，没有则新建
  ftpurl = foldes & List2.List(i) '生成完整路径,包括上传后保持原文件名，list2为文件名
  isput = c.PutImg(List1.List(i), ftpurl) '上传照片，list1存放本地文件路径
  If isput = False Then
    isput = c.PutImg(List1.List(i), ftpurl) '重新上传照片
    if isput=false then exit do
  End If
  DoEvents
  i = i - 1
Loop
end function

'以下是clsftp内容
Private Declare Function InternetOpen Lib "wininet.dll" Alias "InternetOpenA" (ByVal sAgent As String, ByVal lAccessType As Long, ByVal sProxyName As String, ByVal sProxyBypass As String, ByVal lFlags As Long) As Long
Private Declare Function InternetConnect Lib "wininet.dll" Alias "InternetConnectA" (ByVal hInternetSession As Long, ByVal sServerName As String, ByVal nServerPort As Integer, ByVal sUsername As String, ByVal sPassword As String, ByVal lService As Long, ByVal lFlags As Long, ByVal lContext As Long) As Long
Private Declare Function FtpPutFile Lib "wininet.dll" Alias "FtpPutFileA" (ByVal hFtpSession As Long, ByVal lpszLocalFile As String, ByVal lpszRemoteFile As String, ByVal dwFlags As Long, ByVal dwContext As Long) As Boolean
Private Declare Function InternetCloseHandle Lib "wininet.dll" (ByVal hinet As Long) As Integer
Private Declare Function FtpDeleteFile Lib "wininet.dll" Alias "FtpDeleteFileA" (ByVal hFtpSession As Long, ByVal lpszFileName As String) As Boolean
Private Declare Function FtpCreateDirectory Lib "wininet.dll" Alias "FtpCreateDirectoryA" (ByVal hFtpSession&, ByVal lpszDirectory$) As Boolean
Dim linkOn  As Boolean
Dim hSession  As Long

Public Function FtpConnect(Optional ByVal Host$ = vbNullString, _
    Optional ByVal Port& = 0, _
    Optional ByVal user$ = vbNullString, _
    Optional ByVal Password$ = vbNullString) As Boolean
    hinet = InternetOpen(vbNullString, INTERNET_OPEN_TYPE_DIRECT, vbNullString, vbNullString, 0&)
    hSession = InternetConnect(hinet, Host$, Port&, user$, Password$, 1, 0, 0)
    If hSession > 0 Then
      linkOn = True
    Else
      linkOn = False
    End If
    FtpConnect = linkOn
End Function
                                                                  
Public Function PutImg(path As String, ftpurl As String) As Boolean
  If linkOn = True Then
   PutImg = FtpPutFile(hSession, path, ftpurl, 1, 0)
  End If
End Function
                                                                  
Public Function CreatFolde(ByVal path As String) As String
   CreatFolde = FtpCreateDirectory(hSession, path)
End Function