Conditional Sum problem
 

I am linking conditional summary formulas using Excel 2000 in one worksheet
to data in another worksheet. However, I am getting the following error
message: "Run-time error 1004; unable to set the FormulaArray property of
the Range class." I have counted the characters in the correct formula and
they total 180 -- not over 255.

A) I was successful in getting these formulas to work a few days ago. Why
am I now getting this error message?
B) Is there a way to edit a conditional summary formula? I have been
unable to change even one character in the formula without using the Wizard.