I have a worksheet with 2 tabs, Sheet 1 is to be used to display the data I
have on Sheet 2. I named Sheet 2 data and have the following columns:

Dealer Quantity on Invoice Description
Dealer A 1 Product A
Dealer B 1 Product B
Dealer A 1 Product A
Dealer B 1 Product A

On Sheet 1 I created a list in cell A1 so I could select my Dealer. On
Sheet 1 I have a list of the products starting in cell A21. I want to add
quantity sold based on cell A1 that has the dealer's name (thereby compiling
all the dealer's branches into 1) and by product determine what we've sold
them.

So, if A1=data!A:A and A21=data!C:C then sum all that matches in column
data!B:B and return that amount. I've tried sumif with and statements but I
just can't get it right. The closest I've come is
=SUM(IF(AND(($A$1=data!A:A),(Sheet1!A21=data!C:C)) ,data!B:B)) comes back at
least with a 0 and not an error message, what am I doing wrong.

Thanks