Match 2 columns in sheets and return a 3rd column

[GailY10]

I have sheet 1 with January sales in sheet 1 and I want to add February sales from sheet 2 for the same customer/item combination. 

In sheet 1 I want to match column a and column b in a row with the same columns in sheet 2 and return column c of sheet 2 to column d in sheet 1. example attached

[#2]

@GailY10 , that could be

=IFERROR(INDEX(Sheet2!$C$2:$C$10,MATCH(1,INDEX((Sheet2!$A$2:$A$10=A2)*(Sheet2!$B$2:$B$10=B2),0),0)),0)

as in attached file