Employee Schedule

Hi everyone,

I need to schedule employee start and end by half-hour, depending on an expected and needed number

Here are my data :

I need to calculate three more columns :

"Start" : number of employees that need to start at each half hour to reach the expected number

"End" : number of employees that need to start at each half hour. A work day last 8:30 hour for each employee, so this is start + 8:30

"PresentEmployee" : number of employees present at each half-hour (depending on start and end)

here is the results that i expected :

Hre is the results that i have with the following calculated columns, and i d'ont understand why...

START

Start = 
VAR CurrentNum = 'EmployeeSchedule'[Numéro de la demi-heure]
VAR ExpectedEmployees = 'EmployeeSchedule'[ExpectedEmployees]
VAR EmployeesPresent = 
    CALCULATE(
        SUM('EmployeeSchedule'[ExpectedEmployees]),
        FILTER(
            'EmployeeSchedule',
            'EmployeeSchedule'[Numéro de la demi-heure] < CurrentNum
        )
    )
RETURN
MAX(0, ExpectedEmployees - EmployeesPresent)

END

End = 
VAR CurrentNum = 'EmployeeSchedule'[Numéro de la demi-heure]
VAR EndNum = CurrentNum - 17
RETURN
IF(
    EndNum > 0,
    CALCULATE(
        SUM('EmployeeSchedule'[Start]),
        FILTER(
            'EmployeeSchedule',
            'EmployeeSchedule'[Numéro de la demi-heure] = EndNum
        )
    ),
    0
)

PresentEmployees

PresentEmployees = 
VAR CurrentNum = 'EmployeeSchedule'[Numéro de la demi-heure]
RETURN
CALCULATE(
    SUM('EmployeeSchedule'[Start]) - SUM('EmployeeSchedule'[End]),
    FILTER(
        'EmployeeSchedule',
        'EmployeeSchedule'[Numéro de la demi-heure] <= CurrentNum
    )
)

 Thank you very much