How to calculate average based on distinct counts in MDX - ssas

Question

My SSAS cube has the following fact and dimensions with the columns as shown below
FactActivity
DateKey, UserKey, ActivityKey, ActivityCount
DimDate
DateKey, Date, Week, Year
DimUser
UserKey, UserName, Gender
DimActivity
ActivityKey, ActivityName
I have created the distinct count measures of users and dates as follows
[Distinct Users]
COUNT(NONEMPTY([DimUser].[UserKey].[UserKey].Members, [Measures].[ActivityCount])
[Distinct Dates]
COUNT(NONEMPTY([DimDate].[DateKey].[DateKey].Members, [Measures].[ActivityCount])
Both these measures are working correctly as expected when I slice/pivot by ActivityName.
Now I wanted to calculate average days per user, so I created the metric as follows
[Avg Days Per User]
AVG([DimUser].[UserKey].[UserKey].Members, [Measures].[Distinct Dates])
But this is giving me wrong results.! i also tried
DIVIDE([Measures].[Distinct Days], [Measures].[Distinct Users])
Still I get wrong results...what i'm doing wrong?

Answer 1

Maybe just adding in EXISTING will help?
AVG(
EXISTING [DimUser].[UserKey].[UserKey].Members,
[Measures].[Distinct Dates]
)
Although trying to recreate something similar in AdvWks I seem top get a valid return without EXISTING:
WITH
MEMBER [Measures].[Avg Count Per Reseller] AS
Avg
( [Reseller].[Reseller].[Reseller].MEMBERS
,[Measures].[Reseller Order Count]
), format_string = "0.0000"
SELECT
{[Measures].[Reseller Order Count],[Measures].[Avg Count Per Reseller]} ON 0
,{[Promotion].[Promotion].[All Promotions].Children} ON 1
FROM [Adventure Works]
WHERE [Date].[Calendar Year].&[2005];