Trying to create formula to calculate spend per week from a month of data.

Hi,

I have done some basic formulas before, but I'm really struggling to get this one to work.

I have a sheet with a list of job numbers, cost values and dates.
I have a separate sheet in the same workbook to calculate the spend of each job number. I have calculated the total monthly spend with the formula below.
=SUMIF('SITE ORDERS'!$B$3:$B$999, B3, 'SITE ORDERS'!$I$3:$I$999)
=SUMIF(Range, Criteria, Sum range)
=SUMIF(Range of job numbers, Job number, range of order values)

I have gotten so far with the formula to work out the value per week

=SUMIF('SITE ORDERS'!$I$3:$I$999,B3,'SITE ORDERS'!$B$3:$B$999,'SITE ORDERS'!$K$3:$K$999,">="&D1,"<"&E1)
=SUMIF('range of order values, job number, range of job numbers, range of dates, equal or greater than 1st of month, less than 8th of month.


Any input would be appreciated...

Bosy