I need some help with the SUMIFS function (or alternative if that is better suited).

I have a spreadsheet that contains holiday booking information, and I would like to calculate how many people are present on a given day.

I have three columns of data:

- Column A = number of occupants in a booking (i.e. this is the number to be summed if the conditions are met)
- Column B = start date of booking
- Column C = end date of booking

We can consider that Column D = date on which I want to calculate the occupancy (essentially I want to have a column with all the days in a year - e.g. D1 = Jan 1st, D2 = Jan 2nd...).

In plain English, I want to SUM the number of occupants (Column A) on a given date (Column D). The occupants will be summed IF the chosen date (Column D) is equal to or more than the start date of the booking (Column B) AND is less than the end date of the booking (Column C) - i.e. our chosen date in Column D must be between the dates in Columns B and C.

Currently I have the following formula which gives a "0" result:

=SUMIFS($A$2:$A$668, $B$2:$B$668, ">=" & D2, $C$2:$C$668, "<=" & D2)

Any help on the syntax would be greatly appreciated!!!

It would also be useful to have a similar formula that counts the number of arrivals on a given day - at the moment I can only get it to SUM the number of occupants (i.e. I can't get COUNTIF to work... I guess one alternative would be add a single column with "1" in each cell):

=SUMIFS($A$2:$A$668, $B$2:$B$668, ">=" & D5, $B$2:$B$668, "<=" & D5)

I am using Excel 2011 on Mac.

Many Thanks!!