This expression is actually evaluating 2 tuples and then perform the comparison on the evaluated value:
[Reporting Date].[Fiscal].currentmember > [Reporting Date].[Fiscal].[Date].&[2013-03-06]
is :
( [Reporting Date].[Fiscal].currentmember ) > ( [Reporting Date].[Fiscal].[Date].&[2013-03-06] )
where the () represent a tuple (i.e., reference to a cell in the cube). So you're comparing the cell value and not the member dates. I guess what you want is someting like:
select ... {[Reporting Date].[Fiscal].[Date].&[2013-03-06] : [Reporting Date].[Fiscal].[Date].&[2013-03-11] } on 1