while creating trigger upon inert getting error on end

Question

CREATE OR REPLACE TRIGGER PEN_DELTA
  BEFORE INSERT ON PS_GP_RSLT_DELTA
  FOR EACH ROW
  WHEN (NEW.FORWARD_IND = 'Y' AND NEW.GP_PAYGROUP = 'PG PEN')
BEGIN
  FORWARD_IND = 'N';
END;

giving error on

END;

line. is anything I need to change