Semi additive problem...

I have an issue regarding semi additive behaviour which, as a relative newbie, has me stumped.

Take this scenario...

I have a very simple design which consists of a fact table with a single measure (balance), a time dimension and an account dimension. Defined as follows:-

DimAccount (SCD)
AccountKey
AccountType (defines the semi additive behaviour)
Status (can hold the value “Active” or “Inactive”)
StartDate

FactBalances
DateKey
AccountKey
CurrentBalance


The data held is as follows:-
Code:
DimAccount (5 accounts)
AccountKey	AccountType	AccountNumber	Status	StartDate
1		Balance		AC01		Active	2009/01/01
2		Balance		AC02		Active	2009/01/01
3		Balance		AC03		Active	2009/01/01
4		Balance		AC04		Active	2009/01/01
5		Balance		AC05		Active	2009/01/01


FactBalance (3 months of data)	
DateKey		AccountKey	CurrentBalance
20090101	1		1000
20090101	2		1000
20090101	3		1000
20090101	4		1000
20090101	5		1000
20090201	1		1000
20090201	2		1000
20090201	3		1000
20090201	4		1000
20090201	5		1000
20090301	1		1000
20090301	2		1000
20090301	3		1000
20090301	4		1000
20090301	5		1000

My design is configured to use semi additive behaviour for my current balance (LastNonEmpty). So if I drag the “CurrentBalance” into my view window I am correctly told 5000.

Now my account dimension is slowly changing and here is where the problem starts. Amending the data above to show a change in account status to AC01 during the 3 month period gives me the following data:-

Code:
DimAccount (5 accounts but with one historic change row)
AccountKey	AccountType	AccountNumber	Status	StartDate
1		Balance		AC01		Active	2009/01/01
2		Balance		AC02		Active	2009/01/01
3		Balance		AC03		Active	2009/01/01
4		Balance		AC04		Active	2009/01/01
5		Balance		AC05		Active	2009/01/01
6		Balance		AC01		Inactive 2009/02/01

FactBalance (3 months of data)	
DateKey		AccountKey	CurrentBalance
20090101	1		1000
20090101	2		1000
20090101	3		1000
20090101	4		1000
20090101	5		1000
20090201	6		1000
20090201	2		1000
20090201	3		1000
20090201	4		1000
20090201	5		1000
20090301	6		1000
20090301	2		1000
20090301	3		1000
20090301	4		1000
20090301	5		1000

If I now drag in the current balance I still get 5000 (great) but if I drop the attribute “Status” as a row field I get:-


Active 5000
Inactive 1000
Grand total 5000


Not the behaviour I was seeking. I am after the following result:-

Active 4000
Inactive 1000
Grand total 5000


Can anyone help me to achieve this?