I have the following formula in my group totals section of my Crystal Report.
I am simply adding one total to another total.
How can I change this formula to only had totals for the last 12 months and not all totals for all dates and times?

@attempts is the name of the formula

Sum ({tubestats.o_att}, {@medicname})+Sum ({tubestats.n_att}, {@medicname})

Thanks!