how to update functions in excel sheet?

[Inass]

Sirs, I prepared an excel sheet and used functions to convert dates into
numbers then convert these numbers into week number allover the calender
year. then without any reason, all my sheets showed an error in the cells
containing the mentioned formulas and the name of the formulas itself
disappeared from the functions list available in excel. it's really urgent to
know ur answers, because I am preparing reports using the week number. if
this case lasts for long, I'd be wasting much time. Kindly reply as soon as
possible.
Regards

 

[Gord Dibben]

Assuming you used the WEEKNUM Function there most likely is "a reason".

You must have the Analysis Toolpak add-in loaded for this function to work.

Tools>Add-ins. Check the ATP.


Gord Dibben Excel MVP