DAX help - Accounts Receivable Aging

Unfortunately that did not work. But luckily I stumbled on a formula that works. Here it is in case anyone is interested. I'd be happy to hear any suggestions as to improvements to this formula if any exist.

Total AR 0-30 =
VAR EndDate =
    MAX ( 'Calendar'[Date] )
RETURN
    IF (
        MIN ( 'Calendar'[Date] )
            <= CALCULATE ( MAX ('TransactionsTable'[PostingDate]), ALL ('TransactionsTable') ),
        CALCULATE (
            SUM ( 'TransactionsTable'[TransactionAmount] ),
            FILTER ( ALL ( 'Calendar'[Date] ), 'Calendar'[Date] <= EndDate ),
            KEEPFILTERS (
                IFERROR (
                    DATEDIFF ( CustomerTable[CustomerCheckoutDate], EndDate, DAY ),
                    ( DATEDIFF ( EndDate, CustomerTable[CustomerCheckoutDate], DAY ) ) * -1
                )
                    < 31
            )
         )
     )