Hi, I'm new to MDX and am confused about sets, tuples etc. and was wondering if anyone could help me build this mdx function ...

I have the respective dimensions

1. Dimension=Metric
Member= Metric_name MemberProperty= Metric_ky

2. Dimension= Subject
Member= Subject_name MemberProperty= Subject_ky

3. Dimension= Datalayer
Member= Datalayer_name MemberProperty= Datalayer_ky

4. Dimension= MetricDefintions
Member= Metric_ky
Member= Subject_ky
Member= Datalayer_ky MemberProperty= Metric_Target


I need to create a calculated member that will display Metric_Target of MetricDefinitions , based on the the name selected for the other dimensions
ie when the user selects the name for Metric,Subject & Datalayer, I need to retieve their respective property "_ky" and use those keys to drilldown through MetricDefinitions to get the target to be displayed.

Any help will be appreciated ... Thanks