Last Month MDX function for YTD measures in DMR.

[Kyne]

Hello,

I've created Last Month (Named Set) in MSAS Cube as below.

StrToMember("[GL Period].[Financial Year].[Fin Month].[" + Format(Now()-1,"MMM yyyy")+"].lag(1)" )

in GL Period dimension,
it has a hierarchy, which is Financial Year: Day -> Fin Month-> Fin Year
                                                                  Thu,01 Mar 2015   -> Mar 2015 -> 2015

                             and attribute relationship is Day -> Fin Month -> Fin Year

I don't know why but, it doesn't show any result.

if i modify the function as below, it's shown the result, Dec 2014  like the exact result.
StrToMember("[GL Period].[Fin Month].[" + Format(Now()-1,"MMM yyyy")+"].lag(1)" )

but the thing is all the measures for YTD is made with [Financial Year] hierarchy

e.g.
SUM(PERIODSTODATE([GL Period].[Financial Year].[Fin Year],[GL Period].[Financial Year].currentmember),[Measures].[Actual])


Here's the thing.

any suggestion or guide for the last month function with the hierarchy of [GL Period].[Financial Year].[Fin Month]?

Thanks in advance.