Workbook_activate - why doesn't it work

place the code inside (Alt + F11) and paste This_Workbook

Private Sub workbook_activate()
alertTime = Now + TimeValue("00:00:10") 'delay for open indtil execute macro
closingTime = Now + TimeValue("00:00:15") 'delay fra open til close
Application.OnTime alertTime, "EventMacro"

If TimeSerial(6, 0, 0) < Now And TimeSerial(8, 0, 0) > Now Then
Application.OnTime closingTime, "CloseMacro"
End If
End Sub