Comparing 2005 with 2004 YTD

Hi,

I would like to compare current YTD (2005) with 2004 YTD, how do I do that using MDX? ParaLLELPERIOD (Year) and PERIODSTODATE(Year) ?I am not an MDX expert, but I believe something like this should resolve it.

(parallelPeriod([Accounting Week Calendar].[Accounting Year]),[Time Series Analysis].&[1])

Time Series Analysis is a dimension itself, with one record with a field called OLAP (it can be anything) and the value is set to 1.

Thanks
Sutha