Using a Dimension/ Measure in a Where clause of Another Dimension/ Measure in IDT

Hi All

I am building a Universe using Information Design Tool. In the Business Layer, I need to use a created Business Layer Dimension (not Tables) in a Where clause of another dimension as follow:

Dimension: "Current Week No"

     SELECT

          budgets.dbo.Calenderweeks.WeekNo

     WHERE

          budgets.dbo.Calenderweeks.EndDate = convert(SMALLDATETIME, fn CURDATE()})  

Dimension: "Last Week No"

     SELECT

          budgets.dbo.Calenderweeks.WeekNo

     WHERE

          budget.dbo.Calenderweeks  .WeekNo = @Select(Dimension\Current Week No) - 1

The first dimension is working well. However, the "Last Week No" shows NOTHING (I do not get any value)

Anyone can explain why I am not get any value from the second dimension, and how I can use a Dimension/ Measure in a Where clause of another Dimension/ Measure ?

Thanks