CASE Statements Causing Wrong Calculations

HI All,

I am trying to add some conditional calculated fields within client and account data.This code returns exactly the right number of rows and the numbers in the 'closing balance' column are right.

But there is only one calculated field 'closing balance' and when I try to a second calculated field 'opening balance' it all goes wrong. It adds the wrong numbers and the number of rows goes up. See second lot of SQL code with the case statements.

Can anyone tell me what is wrong with the case statements.

--This code return the exact expected results but I
-- need to add more calculated fields.
select DISTINCT
		c.CLIName1,
		c.CLICode,
		g.AGPName1 as [GL Account Group],
		a.COAName1 as [GL Account],
		SUM(l.GNLBalanceBase) AS 'Closing Balance',
		d.DIVName1,
		a.COACode2Code as [GLChart Code 2],
		a.COACode2Name1 as [GLChart Code 2 Name],
		t.CLTName1 as [Client Type]
from DW.vwChartOfAccount a
inner join DW.vwChartOfAccountGroup g
on a.COAAGPID = g.AGPID
inner join DW.vwGeneralLedger l
on a.COAID = l.GNLCOAID
inner join DW.vwClient c
on l.GNLCLIID = c.CLIID
inner join DW.vwClientType t
on c.CLICLTID = t.CLTID
inner join DW.vwDivision d
on l.GNLDIVID = d.DIVID
where  COACode2Code in ('FA301G','FD100G') 
and l.GNLFSMID IN (127,128,129,130)
GROUP BY
		CLIName1
		,CLICode
		,AGPName1
		,COAName1
		,DIVName1
		,COACode2Code
		,COACode2Name1
		,CLTName1
order by d.DIVName1

--I have tried to put the 'closing balance' in a case
--then add a 'opening balance' column but now the returned figures and number of rows is wrong.
select DISTINCT
		c.CLIName1
		,c.CLICode
		,g.AGPName1 as [GL Account Group]		
		,a.COAName1 as [GL Account]	
        ,(CASE
				WHEN l.GNLFSMID IN (127,128,129,130) 
					THEN SUM(l.GNLBalanceBase) OVER (PARTITION BY l.GNLCOAID)
			ELSE '0'
		END) AS 'Closing Balance'
		,d.DIVName1
		,a.COACode2Code as [GLChart Code 2]
		,a.COACode2Name1 as [GLChart Code 2 Name]
		,t.CLTName1 as [Client Type]
		,(CASE
				WHEN l.GNLFSMID IN (127) 
					THEN SUM(l.GNLBalanceBase) OVER (PARTITION BY l.GNLCOAID)
			ELSE '0'
		END) AS 'Opening Balance'
from DW.vwChartOfAccount a
inner join DW.vwChartOfAccountGroup g
on a.COAAGPID = g.AGPID
inner join DW.vwGeneralLedger l
on a.COAID = l.GNLCOAID
inner join DW.vwClient c
on l.GNLCLIID = c.CLIID
inner join DW.vwClientType t
on c.CLICLTID = t.CLTID
inner join DW.vwDivision d
on l.GNLDIVID = d.DIVID
where  COACode2Code in ('FA301G','FD100G') 
GROUP BY
		CLIName1
		,CLICode
		,AGPName1
		,COAName1
		,DIVName1
		,COACode2Code
		,COACode2Name1
		,CLTName1
		,l.GNLFSMID
		,l.GNLBalanceBase
		,l.GNLCOAID
order by d.DIVName1

Thanks for any help.