Hi Alberto,
The UserExit must be applicated only for extraction lines that have 'X' value in ELIKZ field (or EREKZ field):
IF NOT ( <mc02m_0itm>-ELIKZ IS INITIAL AND <mc02m_0itm>-EREKZ IS INITIAL )
SELECT SINGLE LOEKZ INTO <mc02m_0itm>-ROCANCEL
FROM EKPO
WHERE EBELN =<mc02m_0itm>-EBELN
AND EBELP =<mc02m_0itm>-EBELP
AND LOEKZ = 'L'
AND ( ELIKZ = 'X' OREREKZ = 'X' ).
ENDIF.