Perhaps try this sample file with the implemented formula inside:
http://flypicture.com/p.cfm?id=69459
(Right-click on the link: "Download File"
at the top in the page, just above the ads)
File: ellebelle_wksht.xls
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Rgds
Max
xl 97
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GMT+8, 1° 22' N 103° 45' E
xdemechanik <atyahoo<dotcom
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