Divide Measure doesnt works

Good evening, 

I have a problem with my measure : 

Here is my measure : 

MESURE NS =
DIVIDE (
CALCULATE (
SUM ( 'ACD - APPELS'[AppelTraite] );
FILTER ( ALLSELECTED ( 'ACD - APPELS' ); 'ACD - APPELS'[DureeAttente] <= 120 )
);
CALCULATE ( SUM ( 'ACD - APPELS'[AppelTraite] ); ALLSELECTED ( 'ACD - APPELS' ) );
0
)

I would like to use the KPI visualization
So I created a column Target 75% (format decimal number (percentage)

I put :
Actual value: Measure NS
Targert value: Target NS
Trand axis: Month creation

The result is strange:
My line is straight, which would mean that my NS is identical every month. But if I do the math, you will see for yourself that this is not the case.
Can you tell me where I was wrong?

11815/12300 = 0.9605

11038/11639 = 0.948

Thank you