I have one report where the following formula is not working. I did not design this reports and as far as I know the report should run and look for last months sales history data. Also I'm pretty sure this report worked in 2013 so it may be that the formula does not work in 2014 because of it set to look at last months data.
TOTEXT(IF MONTH(CurrentDate)=1 THEN YEAR(CurrentDate)-1 ELSE YEAR(CurrentDate),0,"")
Here is the error I get