Pivot Table newbie confusion...

I have a pivot table based on this data:

Col 1 = customer type
Col 2 = number of customers per acct
Col 3-14 = hours in a particular month (jan - dec)

I'm trying to set up a pivot table that will show me how many customers
received service in a particular month. So in my pivot table I
consolidate the service hours and sum the customer type for a
particular month by choosing a particular column for the "data" section
of the table. This works fine. For example, I can just look at the
service hours in October for each customer type by choosing Col 11
(Oct) for the "data" section.

What I would like to do is know how many customers received service in
a particular month (rather than the total customers I have ever
serviced...which is what happens if I try adding Col 2 to the "data"
section). To do this, the pivot table would need to only sum the
number of customers IF there is a value in the month column I have
selected.

Hopefully that isn't too confusing...

Any ideas?!!