Trying to do a double lookup.

4931857 1 CO
4931857 2 LO
4931890 1 CO
4931890 2 LO
4931890 3 LO

Want to look up the first two columns and get the third column as answer.
I've been interrupted so many times, I don't know where I'm at. This was my
formula but.... D13 would be the order# and S13 would be the dispatch#. In
my range, I don't have any col headings, it looks just like above. We have
Excel 2003.

OFFSET(Sheet1!$A$4:$C$1234,MATCH(D13,OFFSET(Sheet1 !$A$4:$C$1234,0,0,ROWS(Sheet1!$A$4:$C$1234),3),0)-0,MATCH(S13,OFFSET(Sheet1!$B$4:$C$1234,0,0,ROWS(Sh eet1!$B$4:$C$1234),2),0),-2)

Thanks
LCW