MDX: Moving average calculation only gives (null) results - ssas

Question

I am trying to compute a moving average using MDX in SSAS 2014,but all results come out (null).
Reading multiple web references and blog posts makes me think that this should work, giving a 3-month moving average:
With
MEMBER [Measures].[MA3] AS
Avg(
[Date].[Calendar Years].[Month].CurrentMember.Lag(2)
: [Date].[Calendar Years].[Month],
[Measures].[Project Views]
)
SELECT { [Measures].[Project Views], [Measures].[MA3] } ON 0,
[Date].[Calendar Years].[Month] ON 1
FROM [ProjectAccesses]
However, (null) appears in each column.
I'd expect the count of members to be 3 in every case using:
MEMBER [Measures].[C3] AS
Count(
[Date].[Calendar Years].[Month].CurrentMember.Lag(2)
: [Date].[Calendar Years].[Month],
INCLUDEEMPTY
)
but again, no syntax error is detected but all values are (null), leading me to believe that maybe the month-range sets are empty.
I've been around and around this for hours now and have run out of things to try.
Can anyone suggest what might be going wrong please; I'm a newcomer to MDX so it's possible that my query is wrongly structured or there is some error in my cube configuration that I have not been able to find.
Thanks

Answer 1

I believe you need to change
": [Date].[Calendar Years].[Month],"
To
": [Date].[Calendar Years].currentmember,"
[Date].[Calendar Years].[Month] -> should give the level, not the current member which is what you want

Answer 2

I'm surprised that you cannot use the Calendar Years hierarchy throughout. I've added a couple of extra diagnostic measures so you can see what the currentmember function is returning:
WITH
MEMBER [Measures].[MA3] AS
AVG(
[Date].[Calendar Years].CurrentMember.Lag(2)
: [Date].[Calendar Years].CurrentMember,
[Measures].[Project Views]
)
MEMBER [Measures].[C3] AS
COUNT(
[Date].[Calendar Years].CurrentMember.Lag(2)
: [Date].[Calendar Years].CurrentMember,
INCLUDEEMPTY
)
MEMBER [Measures].[Diagn1] AS
[Date].[Calendar Years].CurrentMember.member_caption
MEMBER [Measures].[Diagn2] AS
[Date].[Calendar Years].CurrentMember.Lag(2).member_caption
SELECT
{
[Measures].[Project Views]
, [Measures].[MA3]
, [Measures].[C3]
, [Measures].[Diagn1]
, [Measures].[Diagn2]
} ON 0,
[Date].[Calendar Years].[Month].MEMBERS ON 1
FROM [ProjectAccesses];

Answer 3

I found the solution. I had assumed that i would need to form my set based on a member within my [Calendar Years] hierarchy. However the following, without the hierarchy, works fine (although I can't explain why the original version did not).
With
MEMBER [Measures].[MA3] AS
Avg(
[Date].[Month].CurrentMember.Lag(2)
: [Date].[Month].CurrentMember,
[Measures].[Project Views]
)
MEMBER [Measures].[C3] AS
Count(
[Date].[Month].CurrentMember.Lag(2)
: [Date].[Month].CurrentMember,
INCLUDEEMPTY
)
SELECT { [Measures].[Project Views], [Measures].[MA3] , [Measures].[C3] } ON 0,
[Date].[Calendar Years].[Month] ON 1
FROM [ProjectAccesses]