How to set multiple case statements (3 or more) with alias for each in sql server 2005?

SELECT 
	ISNULL(SUM(PBFSALARY),0) PBFSALARY,
	ISNULL(SUM(CREDITSALARY),0) CREDITSALARY,
	ISNULL(SUM(DEBITSALARY),0) DEBITSALARY
FROM
(
	SELECT
		(CASE WHEN E.Mode ='U' THEN ES.SALARY ELSE 0 END) AS PBFSALARY,
		(CASE WHEN E.Mode ='C' THEN ES.SALARY ELSE 0 END) AS CREDITSALARY,
		(CASE WHEN E.Mode ='M' THEN ES.SALARY ELSE 0 END) AS DEBITSALARY
	FROM
		yourTable
)
AS a