Trouble Calculating the Date Difference between two fields that are the same, but different values

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Days Diff Title Work to Sign Final Commitment =
SUMX (
    VALUES ( 'SPSOrder'[Order ID] ),
    VAR TitleWork =
        CALCULATE (
            MAX ( 'SPSTask'[Completed/Received Date] ),
            'SPSTask'[TaskLookupCode] = "TitleWork"
        )
    VAR SignFinalCommitment =
        CALCULATE (
            MAX ( 'SPSTask'[Completed/Received Date] ),
            'SPSTask'[TaskLookupCode] = "SgnFnlCom"
        )
    VAR Result =
        DATEDIFF ( TitleWork, SignFinalCommitment, DAY )
    RETURN
        Result
)