Thank you for your quick response. I am using Share Point 2010. Here is the MDX query that is defined in the SQL Role in the SSAS cube. I am not sure how to answer your questions, but maybe this query will...
NonEmpty
(
[Dim Local Drilldown Cube].[Fact Key].Members,
(
STRTOMEMBER("[Security Users].[User Name].[" + CustomData() + "]"),
[Measures].[CUBE SECURITY Count]
))