MDX query issue..?

Hi., I am getting NULL values by excuting the following query.., for [Measures].[Ref Period 1],[Measures].[Ref Period 2],[Measures].[Ref Period 4], [Measures].[Ana Period 1],[Measures].[Ana Period 2],[Measures].[Ana Period 3],[Measures].[Ana Period 4], How to retify this pls help me.., and i need to retrive the analysis period values for the reference period customers... -----------------Reference periodWITH MEMBER [Measures].[Ref Period 1] AS ( [Measures].[Teu], [Date].[Week].CurrentMember.Lag(3) )MEMBER [Measures].[Ref Period 2] AS ( [Measures].[Teu], [Date].[Week].CurrentMember.Lag(2) )MEMBER [Measures].[Ref Period 3] AS ( [Measures].[Teu], [Date].[Week].CurrentMember.Lag(1) ) MEMBER [Measures].[Ref Period 4] AS ( [Measures].[Teu], [Date].[Week].CurrentMember )MEMBER [Measures].[AvgTeu-Ref] AS Round(SUM( { [Date].[Week].CurrentMember.Lag(3) : [Date].[Week].CurrentMember } , ( [Measures].[Teu] ) ) / 4,0) ---------------------Analysis periodMEMBER [Measures].[Ana Period 1] AS ( [Measures].[Teu], [Start Date].[Week].CurrentMember.Lag(3) )MEMBER [Measures].[Ana Period 2] AS ( [Measures].[Teu], [Start Date].[Week].CurrentMember.Lag(2) )MEMBER [Measures].[Ana Period 3] AS ( [Measures].[Teu], [Start Date].[Week].CurrentMember.Lag(1) ) MEMBER [Measures].[Ana Period 4] AS ( [Measures].[Teu], [Start Date].[Week].CurrentMember )MEMBER [Measures].[AvgTeu-Ana] AS Round(SUM( { [Start Date].[Week].CurrentMember.Lag(3) : [Start Date].[Week].CurrentMember } , ( [Measures].[Teu] ) ) / 4,0) MEMBER [Measures].[DownFall] as ((([Measures].[AvgTeu-Ref]-[Measures].[AvgTeu-Ana])/100)*100) SELECT { [Measures].[Ref Period 1],[Measures].[Ref Period 2],[Measures].[Ref Period 3],[Measures].[Ref Period 4], [Measures].[AvgTeu-Ref], [Measures].[Ana Period 1],[Measures].[Ana Period 2],[Measures].[Ana Period 3],[Measures].[Ana Period 4], [Measures].[AvgTeu-Ana],[Measures].[DownFall] } ON COLUMNS , TOPCOUNT([Customer Id Sh].[Parent ID].Children,5,[Measures].[DownFall]) ON Rows FROM [Commodities]WHERE ( StrToMember("[Date].[Week].&[2012010101]", CONSTRAINED) , StrToMember("[Start Date].[Week].&[2011010101]", CONSTRAINED) ) -------------------------------------------------------------------------------------