using sumproduct

Giganews Newsgroups
Subject: using sumproduct
Posted by:  Jakobshavn Isbrae
Date: Sat, 10 Jun 2006

I am trying to multiply elements of two arrays of length 10 and sum the 10
products.  The first array is A1 - A10 (vertical).  The second array is C1 -
L1 (horizontal).  This formula works:

I was told that this is dumb and to use sumproduct.  So I try:
=SUMPRODUCT(A1:A10,C1:L1) and all it tells me is  #VALUE!

Now I am sure that this is really simple, but I am stumped and will
appreciate and help anyone can give me.