Need help in computing delta between 2 snapshots

Hi all,

I have a table 'PO Calculations' containing purchase order quantity snapshots identified by "Run Date Key".  I want to compute the "Delta" between the current snapshot with a baseline snapshot for each PO Key.  I created a DAX like below with a baseline Run Date 2022-05-04:

Delta:=
	SUMX(
		VALUES('PO Calculations'[PO_Key]),
		[PO Open Quantity] -
		CALCULATE(
				[PO Open Quantity],
				FILTER( ALL('Run Date'[Run Date Key]),
				'Run Date'[Run Date Key] = DATE(2022, 05, 04)
				),
				'PO Calculations'[PO_Key] = EARLIER('PO Calculations'[PO_Key])
		)
	)

However, the "Delta" is computed only for 2022-05-04 and not other Run Date Key:

I would expect all the Delta should be 0, but it works only for Snapshot on 2022-05-04.

Any help is appreciated.

Best Regards,

Molly