You'll need to help us out a bit as we can't see your formulas or what you are seeing.
When you say "don't work" do you mean they aren't re-calculating? Or do you get errors?
If they aren't recalculating then try pressing F9 (calculate) and if that solves it look at Tools, Options, Calculation and make sure it is set to automatic.
If you get errors, tell us what you get and what the formulas are.