Monthly Wins & Losses - set analysis

[DiegoToll]

Given the following dataset:

Reporting Date	Channel	Client Name	Service	Sale Amount
01/01/2020	AAA	C1	LAD	16
01/01/2020	AAA	C2	LAD	11
01/01/2020	BBB	C1	LAD	6
01/01/2020	BBB	C2	LAD	1
01/01/2020	BBB	C5	LAD	2
02/01/2020	AAA	C1	LAD	8
02/01/2020	AAA	C3	LAD	1
02/01/2020	AAA	C5	MEDICAL	8
02/01/2020	AAA	C4	LAD	7
02/01/2020	BBB	C1	MEDICAL	18
02/01/2020	BBB	C2	LAD	8
02/01/2020	BBB	C3	LAD	10
02/01/2020	BBB	C4	LAD	17
03/01/2020	AAA	C1	LAD	12
03/01/2020	AAA	C3	LAD	5
03/01/2020	AAA	C5	LAD	10
03/01/2020	BBB	C1	MEDICAL	2
03/01/2020	BBB	C3	LAD	15

I need to calculate the New Clients (wins) and Lost Clients (losses) who contracted the service in comparission with previous month

i.e.

My Expression works for fixed months:

But fails when I try to make it dynamic.

I will appreciate any guidance.

[MatheusC]

@DiegoToll 

Based on your print data, given that MonthName's current period is March 2020, you can use max(MonthName).

Look this:

$(=Date#(MonthName(AddMonths(max(FieldMonthName),0)),'MMMM')) – Current

$(=Data#(MonthName(AddMonths(max(FieldMonthName),-1)),'MMMM')) - Previous

Regarts, Matheus