Expression calculation for last 12 months not including this month

[matthewp]

I'm trying to create an expression calculation for last 12 months not including this month.

So for February it would be 2016 FEB to 2017 JAN

I tried

=Count({1<MMMYY ={'>=$(=Date(AddMonths(Today(), -13),'MMM-YY'))<=$(=Date(Today(), 'MMM-YY'))'}>} DISTINCT [MYID])/12

But it didn't work.

[matthewp]

managed top do it using a variable, see answer

thanks for the help

[sunny_talwar]

I am glad it finally worked, but its amazing that one way it worked and other way it did not work. But I guess as long as you get what you wanted, we should be all good