I have a listing of customers. Each row represents one order and in the list
there are multiple orders for each customer. I want to use DSUM to create a
column the displays the total quanity of product bought for that specific
customer for each row that contains that specific customers order. Here's a
sample of data:

A B C D
1 Order# Customer Qty Total for Customer
2 123 Joe 2 DSUM???
3 124 Mark 1 DSUM???
4 125 Joe 4 DSUM???
5 126 Mark 5 DSUM???
6 127 Joe 2 DSUM???


In this example, what I'd like to do is Place a DSUM in the "Total for
Customer" that would display total quantity ordered by the specific customer
(in this case each of Joe's rows would have the qty of 8 returned). I would
like to put the DSUM formula in the first cell under the title row and the
just copy it down and have compute for each row, so each of Joe's rows would
have the value of 8 for the total. Is this possible?

The formula I'm trying is: DSUM(A1:C6,"Qty",B1:B6) - but this isn't working,
its giving me a running sum.

Any help is appreciated.