apllication to detect Logon, Logoff and Switch User events

I already tried the following :

Private Sub SystemEvents_SessionSwitch(ByVal sender As Object, ByVal e As Microsoft.Win32.SessionSwitchEventArgs)
Try
Select Case e.Reason
Case Microsoft.Win32.SessionSwitchReason.SessionLock
ClientStatus(MBSMessage.ClientStatus.Locked)
UserLockUnlockSettingUPdate(MBSMessage.ClientStatus.Locked)
timerMessageRecurrance.Stop()
Exit Select
Case Microsoft.Win32.SessionSwitchReason.SessionUnlock, Microsoft.Win32.SessionSwitchReason.ConsoleConnect, Microsoft.Win32.SessionSwitchReason.RemoteConnect
timerMessageRecurrance.Start()
ClientStatus(MBSMessage.ClientStatus.Login)
UserLockUnlockSettingUPdate(MBSMessage.ClientStatus.Login)
Exit Select
Case Microsoft.Win32.SessionSwitchReason.SessionLogoff
ClientStatus(MBSMessage.ClientStatus.LogOff)
timerMessageRecurrance.Stop()
Exit Select
'added this logon case for DISPLAY_ALERT_DELAY_DURATION feature to work
Case Microsoft.Win32.SessionSwitchReason.SessionLogon
timerMessageRecurrance.Start()
ClientStatus(MBSMessage.ClientStatus.Login)
Exit Select
Case Microsoft.Win32.SessionSwitchReason.RemoteDisconnect
ClientStatus(MBSMessage.ClientStatus.LogOff)
timerMessageRecurrance.Stop()
Exit Select
End Select

every session is raising but logon event is not raising, that is what bothering me.
please do let me know if any other way is der to raise logon event.

Thanks,
Ram