using the "With member"

Hi,
I´m having a problem when I try to subtract my "Share Mes" measure. This measure was created using the "With member". I would like to know if is possible that I do the comparison between April 2007 and March 2007 ("April 2007"."Share Mes" - "March 2007"."Share Mes")


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with set [InterestingProduct] as '{[Produto.Product].[Todos].Children}'
set [TotalPeriods] as 'LastPeriods(13.0, [Periodo.Time].[Todos].[2008].[Q1].[March 2008])'
set [MatPeriods] as 'LastPeriods(12.0, [Periodo.Time].[Todos].[2008].[Q1].[March 2008])'
member [Measures].[Share Mes] as 'Format(IIf(([Produto.Product].CurrentMember.Parent = 0.0), NULL, ([Measures].[Real] / ([Measures].[Real], [Produto.Product].CurrentMember.Parent))), "0.00%")'
member [Produto.Product].[Total of Real] as 'Sum([InterestingProduct])'
member [Measures].[Evolution] as '(Format(((([Produto.Product].CurrentMember / [Periodo.Time].[Mes].CurrentMember.PrevMember) - 1.0) * 100.0), "0.00") || "%")'
member [Periodo.Time].[Total] as 'Aggregate([TotalPeriods])'
member [Periodo.Time].[MAT] as 'Aggregate([MatPeriods])'
select NON EMPTY Crossjoin({LastPeriods(13.0, [Periodo.Time].[Todos].[2008].[Q1].[March 2008])}, {[Measures].[Real], [Measures].[Share Mes], [Measures].[Evolution]}) ON COLUMNS,
NON EMPTY Order({[Produto.Product].[Todos].Children, [Produto.Product].[Total of Real]}, ([Periodo.Time].[Todos].[2008].[Q1].[March 2008], [Measures].[Real]), DESC) ON ROWS
from [SALES_MANUFACTURER_BY_TIME]
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Tks, Concon