Update on After Insert Trigger

Dear All,

I Want to update gl date and trx date with sysdate only for sales return on ra_interface_lines_all.

But when I run this script it has error,  Please help what's wrong with my script.

CREATE OR REPLACE TRIGGER AR.RA_INTERFACE_TRIGGER

AFTER INSERT

ON AR.RA_INTERFACE_LINES_ALL

REFERENCING NEW AS NEW OLD AS OLD

DECLARE

temp VARCHAR2 (10);

BEGIN

IF ra_interface_lines_all.quantity < 0 

THEN

  UPDATE ra_interface_lines_all

  SET trx_date = TRUNC(sysdate),

  gl_date = TRUNC(sysdate)

   where RA_INTERFACE_LINES_ALL.interface_line_attribute6 = :new.interface_line_attribute6 ;

END IF;