DAX vs Sum calculation (Difference in total)

At the day level are the results of the two formulas the same, only at the week level they are different (Difference in total = 5391.02 - 5378.52 = 12.5).
Can someone explain this or what am I doing wrong?

Each day is one line per employee in the data set.

Formules

Aantal_FTE  =

Sum(Fact_Medewerker_Verzuim[Aantal_FTE]),

# FTE in dienst (1) = 

VAR MaxSelectionDate = MAX ('DIM_Kalender'[Date] )

VAR MinSelectionDate = MIN ('DIM_Kalender'[Date] )

RETURN

    CALCULATE (

        Sum(Fact_Medewerker_Verzuim[Aantal_FTE]),

        FILTER (

            'Fact_Medewerker_Verzuim',

            ( Fact_Medewerker_Verzuim[Datum_In_Dienst] <= MinSelectionDate && Fact_Medewerker_Verzuim[Datum_Uit_Dienst] >= MaxSelectionDate )          

        )

    )

Thanks in advance for your help!