HELP!!!

im trying to create a trigger in pl/sql to add 730 days to enddate when begdate is updated or insert if the status is OPEN and the enddate is null...  any help?

CREATE OR REPLACE TRIGGER TRG_CONTRACT
BEFORE INSERT OR UPDATE OF CON_BEGDATE ON CONTRACT
FOR EACH ROW
BEGIN
DECLARE
  CON_STATUS VARCHAR2(10);
  CON_ENDDATE DATE;
  CON_BEGDATE DATE;
BEGIN
  IF CON_STATUS = 'OPEN' AND CON_ENDDATE = NULL THEN
    CON_ENDDATE := CON_BEGDATE + 730;
  END IF;
END;
END;