Lag function not working in calculated measure

Question

I am facing a strange problem while using "Lag" function in calculated measure.
I have a time dimension which consists of date, workday, financial week, Financial Month and Financial Year.
The concept of workday is its a integer number which represents date. In case of holidays this number donot change and remain constatnt till next working day. 
Here workday no remains 460 as 20120708 is a holiday.27 and 28 denotes FinancialWeek.
Now basically I want to find previous wokdays count.
with member [Measures].[Prev Count]
AS
sum(
          existing [Date].[Workdayno].[Workdayno].Members,
 ([Date].[Workdayno].lag(1),[Measures].[Fact Count]))
Select { [Measures].[Prev Count]} on 0,
{[Date].[Calendar].Members} on 1 from [My Cube]
Where([Date].[Calendar].&[20120709])
What I expect that It will give me sum of counts where wokday no is 460.
But its showing null value.
with member [Measures].[PrevCount]
As
SUM(EXISTING [Processing Date].[Workday].[Workday].MEMBERS,([Processing Date].[Workday].LAG(1),[Measures].[Sequenced Records]))
SELECT {[Measures].[PrevCount]} ON 0 FROM --[E2Eitem]
WHERE([Processing Date].[E2E Calendar].[Date].&[20120709])
It looks like existing function is failing to exist the member related to date??
Any suggestion.

Answer 1

Try using
with member [Measures].[Prev Count]
AS
sum(
          existing [Date].[Workdayno].[Workdayno].Members,
 ([Date].[Workdayno].currentmember.lag(1),[Measures].[Fact Count]))
Victor Rocca