Try this and let me know if it works
SELECT
{[Measures].[Operational Transactions Count]} ON COLUMNS,
{[Date].[Hierarchy - Fiscal].[Fiscal Week].&[2012]&[48]} ON ROWS
FROM
(SELECT {[Financial Transaction Channel].[Transaction Channel Desc].&[POS],
[Financial Transaction Channel].[Transaction Channel Desc].&[CONCIERGE]} ON COLUMNS
FROM EDW)
Mack