TOPCOUNT query not working

When I run the query below I only get 2 records back. If I drop the TOPCOUNT, I get 508 records.

Why is it not giving me the top 5 from the 508 records? What am I missing?

Regs

Jon

with
	MEMBER Measures.[EmailCount] as IIF(ISEMPTY([Measures].[Tran Count]), 0 ,[Measures].[Tran Count])
	MEMBER Measures.[IncomePerEmail] as
		[Measures].[Amount]/ IIF(Measures.[EmailCount] = 0, 1 , Measures.[EmailCount] )
    MEMBER Measures.[Income Range] as
	 CASE
          WHEN Sum(EXISTING [Dim IFA Details].[Parent Key].[Adviser Group].Members,
                Measures.[Amount] ) <= 10000 THEN  '0-10000'
		  WHEN Sum(EXISTING [Dim IFA Details].[Parent Key].[Adviser Group].Members,
                Measures.[Amount] ) <= 50000 THEN  '10001-50000'
		  WHEN Sum(EXISTING [Dim IFA Details].[Parent Key].[Adviser Group].Members,
                Measures.[Amount] ) <= 100000 THEN  '50001-100000'
		  WHEN Sum(EXISTING [Dim IFA Details].[Parent Key].[Adviser Group].Members,
                Measures.[Amount] ) <= 200000 THEN  '100001-200000'
		  else '> 200000'
		  end

SELECT   {  [Measures].[Amount] , Measures.[EmailCount], measures.[Income Range], Measures.[IncomePerEmail] }
  ON COLUMNS,
 TOPCOUNT(
 NONEMPTY([Dim IFA Details].[Parent Key].[Adviser Group].Members, Measures.Amount)
 , 5
 , Measures.[IncomePerEmail]
 )
having Measures.[Income Range] = '10001-50000'
on rows
FROM [Income and Emails Cube]
where [Dim Date].[Fiscal Year].&[FY 13/14]