Count measure with date intelligence

Hello guys, I've a question with count in measures.

I've a initial matrix as distinct count of client that bought on these months.
Column: Date
Row: ID Client

In other words, the acumulated of sales in 12M is like: 

measure_Sale_12M = 
CALCULATE(DISTINCTCOUNT('General Key'[Client ID]),
DATESBETWEEN(Calendar[Date],
            DATEADD(
            LASTDATE(Calendar[Date]),-12,MONTH),
            LASTDATE(Calendar[Date]) 

))

In this way, I've calculated the difference of month and month-1 to result like this: 

measure_Sale_12M-1 = 
CALCULATE([measure_Sale_12M],
 DATEADD(Calendario[Date], -1, MONTH)

)

and then

metric_final = [measure_Sale_12M]-[measure_Sale_12M-1]

resulting this:

This way I got active client (result 0), new client (result 1) and lost client(-1) in table. 

But my problem is here. How can I count the 0? I'm just using matrix visual, I don't have table only for this operation, just a general database. How do I a measure to give count this?

In practical example, PBI show me this: 

Thank you,