Calendar Date Context

Hello , 

 There is a measure

Unpaid Invoice Days = 
VAR _tbl =
    FILTER (
        ADDCOLUMNS (
            SUMMARIZE (
                Debt;
                Debt[DocumentNo];
                Debt[KeyCode];
                Debt[PaymentDate]
            );
            "Saldo"; CALCULATE ( SUM ( Debt[Amount] ) );
            "InvoiceDate"; CALCULATE ( MAX ( Debt[DocumentDate] ) ) //For knowing which Date Invoice is unpaid 
        );
        [Saldo] > 0 // to filter Unpaid Invoices
    )
VAR _min = MINX ( _tbl; [InvoiceDate] )
VAR _max = MAXX ( _tbl; [InvoiceDate] )
RETURN
    CALCULATE (
        DATEDIFF ( _min; _max; DAY );
        FILTER (
            ALL ( 'Calendar'[Date] );
            'Calendar'[Date] >= MAX ( 'Calendar'[Date] )
        )
    )

It working fine, but when i put it with Calendar[Date] column it filter's my _tbl rows. I tried to wrap DATEDIFF ( _min; _max; DAY ) function with CALCULATE FILTER ALL pattern, but it dont work. What is wrong ?

pbix Sample file - https://1drv.ms/u/s!Ag3StL_v1twMoVIBrE0WPgoN3QT4?e=4MbQ5h

Thank You