sum values of last months

[jvargasmayorga]

Hello Community.
I have the following problem.
This is a sum of quantities table, grouped by time dimension (Year and Month)

Cant. Trx

Sum(Cantidad_transito)

What I need now is to add the values of the last 3 months, but for each month.
For June: You must add the values of April, May and June
For February: You must add the values December 2021, January and February. Something like that:

In this sum I am having problems. I use the following formula and it gives me the wrong result (same as a simple sum)
Qty trx 3 Month =>

sum({<Fecha_transito={">=$(=MonthStart(AddMonths(Max(Fecha_transito),-2)))<=$(=MonthEnd(AddMonths(Max(Fecha_transito),0)))"}>} Cantidad_transito)

Using this formula (adding  TOTAL), it only considers the sum of the last 3 months and that result places it in all the same months.

sum({<Fecha_transito={">=$(=MonthStart(AddMonths(Max(Fecha_transito),-2)))<=$(=MonthEnd(AddMonths(Max(Fecha_transito),0)))"}>} TOTAL Cantidad_transito)

I think the solution would be like NOT considering the time dimension in the sum, but showing it each in its own time, it's very confusing, any idea how to solve it? Need this result.

Thanks

[jvargasmayorga]

hello.
I did what you indicated and it seems to be ready, when I do the validation there are few records that do not match. I will review the data now, to confirm if it is ok. But you helped me a lot.
Thank you