Try and play with something like below.
WITH MEMBER [Measures].[YTD untill previous week] AS
Sum(
YTD(Parallelperiod([Date].[Calendar Weeks].[Calendar Week],1,[Date].[Calendar Weeks].[Calendar Week].&[10]&[2008])),
[Measures].[Internet Sales Amount]
)
SELECT
{
[Measures].[Internet Sales Amount],
[Measures].[YTD untill previous week]
}
ON COLUMNS,
[Date].[Calendar Weeks].[Calendar Week].&[10]&[2008]
ON ROWS
FROM [Adventure...