With two variables defined as follows:
I got 15 using this
and 14 using this
probably linked to the first using/expecting a timestamp and the 2nd a number. But I don't know for sure. If your fields Date_de_Fin and Date_de_creation are timstamps use floor() to make them into numbers.
Hope this helps
Thanks to you two for your help.
I was not using ([Date_de_fin])- ([Date_de_creation]) because I have some empty fields. But in fact it's the best way, so I manage to avoide calculating the expression when the field is NULL and it works now.
DayNumberOfYear is using 366 days years, so that's why february has always 29 days, even when it should'nt ...
I have now to check if it works betwen two different year, but it should be ok.
Again, thank a lot for you answers.