How to use event handler in windows service

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VB

Dear sir/s,

I am new in windows services, i have been developing new windows services for detecting system date changes.
as soon as system date changes then windows services should write log.

for that i have written following code,

 Protected Overrides Sub OnStart(ByVal args() As String)
   AddHandler SystemEvents.TimeChanged, AddressOf SystemEvents_TimeChanged
End Sub

Private Sub SystemEvents_TimeChanged(ByVal sender As Object, ByVal e As EventArgs)
    WriteToFile("System Time has been changed")
End Sub

But when i change system date then windows service does not fire above event.
Please help me.
Thank you.