ERROR!!! My formula gives inconsistent Results

Hi,

I have a spreadsheet that calculates monthly revenue automatically between two dates. For some reason, I can't attach the file so I just print screen it.

annual revenue.PNG


My formula for column N is

=IF(OR($F4="",$K4="Cancelled"),0,MAX(0,MIN($G4,P$2)-MAX($F4,O$2)+1))

whereas,
F is Check-In Date
K is the Status of the Reservation
G is the Check-out Date
O is the start date of the month
P is the end date of the month

I noticed that if my check-in date was still the year 2013 the result is wrong like Row 23; Column N should be 4 not 5.

all of those rows have +1 and yields correct results except row 23.

i noticed it has something to do with my check-out date. it is the check-out date that doesn't calculate properly.

I just noticed it now, that is on the check-out date that yields incorrect result. Do you know how to fix it? Cause if I remove the +1 then all results that has check-in date sometime in january would then be incorrect.

OMG!!! it works.

Thank you so much.