But I don't receive any output, unless I select both years. I do not want to do this, though, because it would mess up the rest of my report.
Also, this applies only tor this specific formula. When simply calculating the mean or the median without any aggregation*, my report will display previous year data without any problems, even though only one year is selected.
thanks for your reply and your ideas. I wouldn't want to use variables, as I would want to display values for both years in one chart at the same time so I can compare them. Also, I would have to restructure my whole report due to this one formula.
Combining the previous year with the aggregation dimension won't do the trick. Also, I made sure before, that the aggregation dimension will never have the same value for two different years.