Chip Pearson has some very nice notes:
http://www.cpearson.com/excel/datedif.aspx

Mijosuva wrote:

Dear Expert

I try to use DateDiff but it doesn't work, when I try to use this simple
function excel say #NAME?

This is what I have

Function session_num(start_date As Date, today_date As Date) As Long

'Determine the # of weeks between today date and Start Date

session_num = DateDiff("ww", today_date, start_date)

End Function

--

Dave Peterson