How to compare data at 2 different dates

Hi Sylvain74 ,

I updated your sample pbix file(see attachment), please check whether it can get your expected result.

1. Update the formula of measure [Scenario - Delivered Quantity ] as below

Scenario - Delivered Quantity = 
VAR _selactdates =
    ALLSELECTED ( 'Scenario Actual Date'[VALUATION_DATE] )
VAR _selscedates =
    ALLSELECTED ( 'Scenario Dates'[VALUATION_DATE] )
RETURN
    CALCULATE (
        SUM ( 'Contract Deliveries'[DeliveredQuantity] ),
        FILTER (
            'Contract Deliveries',
            'Contract Deliveries'[ValuationDate]
                IN _selactdates
                || 'Contract Deliveries'[ValuationDate] IN _selscedates
        )
    )

2. Create a new measure as below to get the sum of contract quantity

Scenario - ContractQuantity = 
VAR _selactdates =
    ALLSELECTED ( 'Scenario Actual Date'[VALUATION_DATE] )
VAR _selscedates =
    ALLSELECTED ( 'Scenario Dates'[VALUATION_DATE] )
RETURN
    CALCULATE (
        SUM ( 'Contract Deliveries'[ContractQuantity] ),
        FILTER (
            'Contract Deliveries',
            'Contract Deliveries'[ValuationDate]
                IN _selactdates
                || 'Contract Deliveries'[ValuationDate] IN _selscedates
        )
    )

Best Regards