please help:

is it possible to create a trigger with a subquery ?

i have a table "track" with fields (action,action_date,user,os_user)

my trigger:

CREATE or replace tirgger score_track
AFTER insert or update or delete on score

if inserting then
insert into track values
('insert',sysdate,user,(select osuser from v$session where schemaname in (select user from dual)));
elsif ....

i keep getting a PLS-00103.