Damn triggers and NEW

Okay, I'm obviously doing something wrong but what?

I have a trigger defined as:

create or replace function cms_user_id_insert_tgr_1 ( )
returns trigger
as '
begin
execute ''
select 1
from
individuals i
,user_roles ur
,roles r
where
r.name = ''''CMS''''
and
ur.role_id = r.id
and
ur.individual_id = i.id
and
i.id = NEW.'' || quote_ident(TG_ARGV[0]) || ''
and
i.active is true'';
if not found then
raise exception ''TRIGGER: UserNotFound'';
end if;

return NEW;
end;
'
language 'plpgsql';

create trigger cms_user_id_insert before insert
on groups
for each row
execute procedure cms_user_id_insert_tgr_1 ( 'principal_user_id' );

And when this trigger gets kicked I get a message about NEW used in a non-rule
query. The postmaster log is below.

I'd appreciate some pointers on this as it appears new/old can't be used in an
execute statement in triggers but that sounds completely wrong.

--
Nigel J. Andrews

2003-06-17 10:09:08 LOG: query: insert into ttacms1.workflow_events (
article_id,
after_status_id,
xml_changes,
event_dt,
notes,
before_status_id,
user_id,
id
)
(select
article_id,
after_status_id,
xml_changes,
ur.role_id = r.id
and
ur.individual_id = i.id
and
i.id = NEW.' || quote_ident( $1 ) || '
and
i.active is true'
2003-06-17 10:27:50 LOG: query: SELECT 0
2003-06-17 10:27:50 LOG: query:
select 1
from
individuals i
,user_roles ur
,roles r
where
r.name = 'CMS'
and
ur.role_id = r.id
and
ur.individual_id = i.id
and
i.id = NEW.principal_user_id
and
i.active is true
2003-06-17 10:27:50 ERROR: NEW used in non-rule query