Hi
I am using WEEKNUM function in a series of MACRO routines. Problem is they
work really well than sometimes for no apparent reason I get the #NAME error
command. I go back into the Add-Ins Menu, remove the selection on Analysis
Tool Pak, go out. Then go back in and re-select then Analysis Tool Pack - it
then works again. It took me a little while to work through this fix - and
lot of hair pulling!!

Does anyone have any suggestions as to what may be causing it?

Regards