Hoping someone can please help me....

Running Excel 2003, I have a worksheet, on which each row represents product
shipment data.

L2:L133 represents product shipment date
P1 represents current date
Column O=NETWORKDAYS(L2,,$P$1)-1
To calculate the actual # of days elapsed between shipment and current date.

N2:N133=Shipment value
N134="Total" (name defined)

Q1=SUMIF(O:O,"=12",N2:N133) To obtain shipped total matching or exceeding
12 days.
R1=Q1/Total, to obtain % of total which has met or exceeded 12 days.

Formulas seem to calculate correctly, yet if I go back and "add the shipment
values which match or exceed the desired 12 days, I get a different total,
than the system calculates in Q1.

Any ideas?

TIA,
Sandi