Set analysis issue / Count of the defect the last month

[Jérôme5625]

Hello,
a simple question for those who are more experienced than me. I would like to display the sum of the defects of the previous month chosen. The sum of defects of the selected month works but as soon as I add "-1" for the previous month, the result becomes 0. I think this must be due to a syntax problem.

Can you help me?

Set analysis: Count({$<[Data.Mois]={$(=Only([Data.Mois])-1)}>}[Data._kizeo_id]) 

[BrunPierre]

Count({$<[Data.Mois]={"$(=Only([Data.Mois])-1)"}>}[Data._kizeo_id]) 

[vinieme12]

is Month a Text field or a Numeric field ?

Also simply  substracting  MonthNumber  -1 will fail if you select January which will be 1-1 = 0

You should actually be using the actual Date field to refer previous month

Latest/Selected Month

Count({<Datefield={">=$(=Date(Monthstart(Max(Datefield)))<=$(=Date(Max(Datefield)))"}>}[Data._kizeo_id]) 

Previous Month

Count({<Datefield={">=$(=Date(Monthstart(Max(Datefield),-1)))<=$(=Date(Monthend(Max(Datefield),-1)))"}>}[Data._kizeo_id]) 

[Jérôme5625]

Hi Vinieme12, 

Thanks for your feedback.

I tested : Count({<Datefield={">=$(=Date(Monthstart(Max(Datefield),-1)))<=$(=Date(Monthend(Max(Datefield),-1)))"}>}[Data._kizeo_id]) 

but the result is always the current month and not the previous month.
Attached is the screenshot which shows that the months M-1, M -2 and M-3 are always identical to the selected month.
Thanks in advance for your help

[vinieme12]

Can you post the exact expression you used? A full snapshot of the expression editor 

[Jérôme5625]

Attached the snapshot of the expression editor for the last month.

Thanks for advance for your help

[vinieme12]

You need to replace Datefield with THE ACTUAL DATE FIELD 

Just like you have Data.Mois  you must have a field that has date values! Use that field