Option Explicit
 
Public Const NERR_Success = 0
   Public Const ERROR_PRIVILEGE_NOT_HELD = 1314
   Public Const ERROR_LOGON_FAILURE = 1326
 
   Public Const LOGON32_PROVIDER_DEFAULT = 0
   Public Const LOGON32_LOGON_NETWORK = 3
 
   Public Declare Function LogonUser _
     Lib "Advapi32" _
     Alias "LogonUserA" _
     ( _
     ByVal lpszUsername As String, _
     ByVal lpszDomain As String, _
     ByVal lpszPassword As String, _
     ByVal dwLogonType As Long, _
     ByVal dwLogonProvider As Long, _
     phToken As Long _
     ) _
   As Long
 
 
   Public Declare Function CloseHandle _
     Lib "Kernel32" _
     ( _
     ByVal hObject As Long _
     ) _
   As Long

Private Sub cmdLogOn_Click()
 
     Dim sUserName As String, sDomainName As String
     Dim sDCName As String, sPassword As String
     Dim lToken As Long, lRet As Long
 
     sUserName = txtUsername.Text
     sDomainName = txtDomain.Text
     sPassword = txtPassword.Text
 
     lRet = LogonUser(sUserName, _
                      sDomainName, _
                      sPassword, _
                      LOGON32_LOGON_NETWORK, _
                      LOGON32_PROVIDER_DEFAULT, _
                      lToken)
 
     If lRet = NERR_Success Then
 
       Debug.Print "Error during Logon process"
 
       Select Case Err.LastDllError
         Case ERROR_PRIVILEGE_NOT_HELD
           ' Keine Rechte für LogOnUser
           Debug.Print "A required privilege is not held by the client"
 
         Case ERROR_LOGON_FAILURE
           ' entweder Username oder Passwort ist falsch.
           Debug.Print "User Name or Password is not correct"
 
         Case Else
           ' sonstige Fehler
           Debug.Print " Unspecified Error: " & Err.LastDllError
       End Select
 
     Else
       ' Erfolgreich
       Debug.Print "Successfully logged on"
       lRet = CloseHandle(lToken)
 
     End If
 
   End Sub