O que tem de errado nesta função SQL?

CREATE OR ALTER FUNCTION fnSALARIO_LIQUIDO (
	@ANOCOMP_N AS INTEGER,
	@MESCOMP_N AS INTEGER,
	@NROPERIODO_N AS INTEGER,
	@CHAPA_S AS VARCHAR(20)
) RETURNS DECIMAL(18,4)
AS
BEGIN
	DECLARE @RETORNO AS DECIMAL(18,4)

	SET @RETORNO = (SELECT (ISNULL((SELECT SUM(X.VALOR) FROM PFFINANC X (NOLOCK)
                        INNER JOIN PEVENTO Y ON (Y.CODIGO = X.CODEVENTO AND Y.CODCOLIGADA = X.CODCOLIGADA)
                        WHERE X.CHAPA = A.CHAPA AND
                        X.ANOCOMP = @ANOCOMP_N AND X.MESCOMP = @MESCOMP_N AND X.NROPERIODO = @NROPERIODO_N
                        AND Y.PROVDESCBASE = ''P''), 0)
                        
                    -  ISNULL((SELECT SUM(X.VALOR) FROM PFFINANC X (NOLOCK)
                        INNER JOIN PEVENTO Y ON (Y.CODIGO = X.CODEVENTO AND Y.CODCOLIGADA = X.CODCOLIGADA)
                        WHERE X.CHAPA = A.CHAPA AND
                        X.ANOCOMP = @ANOCOMP_N AND X.MESCOMP = @MESCOMP_N AND X.NROPERIODO = @NROPERIODO_N
                        AND Y.PROVDESCBASE = ''D''), 0))
					FROM PFUNC A
					WHERE A.CHAPA = @CHAPA_S)
END

GO

SELECT A.CHAPA, A.NOME, SALARIO_LIQUIDO = dbo.fnSALARIO_LIQUIDO(2023, 11, 1, A.CHAPA)
FROM PFUNC A
WHERE A.CHAPA = ''00802''