Formula to work out number of people receiving support hours in a given week

[mrsdeapsleap]

I have attached my spread sheet for you. I need to find a formula that will work out of the service users listed in cells A13:A18, how many received support hours per individual(shown in column C) for the week specified. My results box is A90 to B96; the week dates are shown here, but these are picked up from sheet 2, cells A17 to B21. I already have a formula that counts the amount of services users on service for that week, =SUMPRODUCT(($D$13:$D$21<=Sheet2!B17)*($E$13:$E$21>=Sheet2!A17)) ; this only picks up the amount of service users for that week. What I want to add onto this formula is only count if cells C13:18 are greater than zero (as well as between the dates shown); i.e. the individuals actually had more than zero hours support for that week.

Can this be done? If you need clarification on anything above, please let me know!