MDX Newbie: How to combine some members to create a new member at same level (but not a calc. member)

I have a Dimension Items with first level ItemType.I want to create a member which combines some of the existing members.For example, I have members [Items].[ItemType].Deposit and [Items].[ItemType].GiftVouchersand I want to "pretend" that I actually have a member [Items].[ItemType].DepositsAndVouchersIt sounds like Aggregate would do what I want:WithMember [Items].[ItemType].[DepositsAndVouchers] as 'Aggregate({[Items].[ItemType].[Deposit], [Items].[ItemType].[GiftVouchers]})'select [Items].[ItemType].[DepositsAndVouchers] on columns,[Measures].[AmtReceived] on rowsLogically I thought this would work ... but I get nothing (using Mondrian actually)So I have a conceptual problem with how MDX works, perhaps.