On Sat, 8 Nov 2008 05:54:01 -0800, LionR
wrote:

I set up a formula adding a set of numbers in a column, e.g.=sum(c1:c34).
The formula is correct but I got a zero as an answer. I set up the same
formula in another column and it gives me the correct answer, e.g. $2,500. I
tried copying this formula to the first one on the same row. And it returns
$2,500.

What is going on?

Possibly your "numbers" in c1:c34 are text.

What do you get if, in some cell, you type: =istext(c1)

How are the data entered in column C?
--ron