Oracle - IF Statement into WHERE Clause

I should translate the c # code into stored procedure in oracle. I did a store procedure with case when in the where but the right data does not come back to me. Where am I wrong?

The problem is to manage the IFs of the input parameters.

Oracle:

    CREATE OR REPLACE PROCEDURE SP_S_RICCFEMESSE 
(
    NUMEROCV        IN VARCHAR2,
    PROFILO         IN NUMBER,
    SALAES          IN NUMBER,
    DATAINIZIO      IN VARCHAR2,
    DATAFINE        IN VARCHAR2,
    ric_carteemesse OUT SYS_REFCURSOR
)


AS 
BEGIN

OPEN ric_carteemesse FOR
SELECT DISTINCT A.*
                ,DESCARDPRFCFR AS TIPO_CARTA
                ,TO_CHAR(DATNAS,'DD/MM/YYYY') AS DATA_DI_NASCITA 
                ,TO_CHAR(A.DATIVOPSA,'DD/MM/YYYY HH24:MI:SS') AS DATA_EMISSIONE 
                ,TO_CHAR(DATINIVALRTA,'DD/MM/YYYY') AS INIZIO_VALIDITA_CARTA 
                ,TO_CHAR(DATFINIVALRTA,'DD/MM/YYYY') AS FINE_VALIDITA_CARTA 
                ,C.S_DENOMINAZIONE AS SALA_ES 
                ,CASE 
                    WHEN NVL(SCDUP,0) = '0' 
                    THEN 'NO' 
                    WHEN SCDUP > 0 
                    THEN 'SI' 
                END AS DUPLICATO 
FROM 
DEMIRTAFRC A 
INNER JOIN SMART_CARD B 
    ON A.CODSRE = B.COD_SM 
LEFT JOIN RIVENDITA C 
    ON B.S_POSTAZIONE_UM = TO_CHAR(C.COD_RIVENDITA) 
INNER JOIN DANACARDPRFCFR D ON A.CODPRF= D.CARDPRFCFR 
WHERE 
    (B.D_ELETTRIFICAZIONE BETWEEN TO_DATE(DATAINIZIO,'DD/MM/YYYY') AND TO_DATE(DATAFINE,'DD/MM/YYYY') 
    AND A.MDLCSG = 'CBM' AND CODSRE IS NOT NULL)
    AND NUMEROCV = (CASE WHEN NUMEROCV <> '' 
                         THEN A.CODRTA
                         ELSE null 
                    END)
    AND PROFILO = (CASE WHEN PROFILO <> 0 
                        THEN B.COD_REQUISITI
                        ELSE null 
                   END)
    AND SALAES = (CASE WHEN SALAES <> 999
                       THEN B.S_POSTAZIONE_UM
                       ELSE null 
                  END)
ORDER BY A.DATETR DESC;

END SP_S_RICCFEMESSE;