Glad you finally solved it, and thanks for getting back with the solution.

I think it works right for you if you go down to the date level of the hierarchy, correct?

WITH MEMBER [Measures].[Test] AS

SUM

(

EXISTING [Date].[Calendar].[Date].Members,

( [Measures].[Order COUNT] - (ParallelPeriod([DATE].[Calendar].[Calendar YEAR], 1), [Measures].[Order COUNT]) )

)

SELECT{[Measures].[Test], [Measures].[Order COUNT]} ON COLUMNS,

[Date].[Calendar].members ON ROWS

FROM [Adventure Works]