I have a report where I may or may not be pulling data for 2 different years so that I can compare numbers for different categories, depending on how some parameters are answered. I then have running totals with formulas to evaluate, so that each category for each year has the proper numbers. I also have formatted the field for the comparison year where you can put in a N for a certain parameter and it will suppress the comparison year. Here's the bottom line:

For example, I need the running total named CTCountARSON to not run if the parameter CompareYN = N.

The reason for this is, even if the comparison fields are suppressed because the CompareYN parameter is set to N, the running totals will still run. Those particular running totals use the parameters CBeginningDate and CEndingDate, which would be blank if CompareYN is answered no. I will then get an error from the running totals saying the formulas can't run because CBeginningDate and CEndingDate are not defined.

Any help with this would be appreciated.

In the Evaluate portion of the running total you could just have CTCountARSON = "Y"

No problem.  That is why we are all here.  I am not an expert in other areas.