Copying data with triggers

Hi all,

In the database I'm designing, I want to have audit tables that keep a log 
of all inserts, updates and deletes that occur
on any table.

e.g. If i had a table Info,
create table Info ( info_id SERIAL,                          some_data text
)

I would also have a corresponding audit table

create table AudInfo (aud_key_id SERIAL,                               info_id int4,
some_datatext,                               aud_operation_type,                               aud_log_time timestamp
defaultnow()
 
)

now I tried creating a trigger on Info, so that whenever an insert occurs, 
the records are copied to the audit table.

create function tp_info () returns opaque as 'begin    -- insert into audit table    insert into AudInfo (info_id,
some_data,aud_operation_type) values 
 
(new.info_id, new.some_data, ''i'');    return new;end;
' language 'plpgsql';

create trigger tp_info before insert on Infofor each row execute procedure tp_info();

This doesn't work however. A parse error occurs in the first line.
I suspect that I cannot insert a record into another table in a trigger. 
I'm not sure why though.

Anybody else done similar operations within a trigger procedure? Or know of 
a work around?

Cheers,
Keith.