First date from date column

[giorgilomidze]

I need to have total number of days after first operation. Thus I'm trying to use this formula 
datediff(firstdate([datecolumn]),lastdate([datecolumn]),days) but its not working. am i doing something wrong?

[giorgilomidze · Accepted solution]

I Used date format and it resolved problem  (taking .date from date/time format)

DATEDIFF(FIRSTDATE([Datecolumn].[Date]),LASTDATE([Datecolumn].[Date]),DAY)

[theitguy]

Have you tried DAY instead of days as well?

datediff(firstdate([datecolumn]),lastdate([datecolumn]),DAY) 

[giorgilomidze]

It is "Datediff" Formula Option.