Implications Of Using SET Statements

After I created the following SET statement in my cube it appears as if SSAS is always calculating it before I can switch to the browser view in BIDS. So it almost becomes a performance issue. Also I cannot see it from Excel, why would that be?




Code Snippet
CREATE SET CURRENTCUBE.[Top10Count]
AS TopCount(
CROSSJOIN(
{[DIM IMPORTMONTH].[REVIEWPERIOD].DefaultMember},
{[DIM DMDUNIT].[DMDUNIT].Children},
{[DIM DMDGROUP].[DMDGROUP].Children},
{[DIM LOC].[LOC].Children}
)
,10,[Measures].[QTY]) ;







Here is my questions, it would be great if somebody could advice me:



Why can't I see the SET within Excel although I have marked it visible and given it a name? I see other SETs.


In order to not see empty combinations I would like to add the nonempty() function but cannot get it to work. Where would I put it?


If a user wanted to see the Top10 rows based on QTY I'd expect her/him to pick the SET above and the required dimensions along with the QTY measure and the list should come up, is that correct?

My customers use Excel as the front end so I nees a solution that supports that.

Thanks for any help in advance.

Regards,
Dirk