Sum to a textbox

[Becky]

I know how to do this if everything was weighted equally
but not if there are many weights.

I have stores that are assigned how many times a month
they must be seen and for how long. I have thousands of
these.

tblHours: hoursID, hours
tblFrequency: FreqID, Frequency
tblMain: MainID, AccountID, LocationID, ClientID, FreqID,
HoursID,MerchandiserID, SpecialNotes, StoreNumber

I have frquency as Bi-Monthly, Monthly and weekly. I
have qrueries that figure out the separate hours but how
do I pull those together in the form and recaulate those
hours when new filters are run on the form?

Right now the textbox has the source as = =nz(Sum
([hours]),0) but of course the total isn't correct.

Thanks,
Becky