Troubles with plPgSQL.

I attach(create language) language PL/pgSQL in PG and
create test function (cut it from help ) :

--Просто склеить строки в одну
CREATE FUNCTION ct1(text, text) RETURNS text AS '
BEGIN
RETURN $1 || $2;
END;
' LANGUAGE 'plpgsql';

So that is my log :

pvic(at)ses:~ > pslq
stoage
bash: pslq: command not
found
pvic(at)ses:~ > psql
storage
Welcome to the POSTGRESQL interactive sql
monitor:
Please read the file COPYRIGHT for copyright terms of
POSTGRESQL
[PostgreSQL 7.0.2 on i686-pc-linux-gnu, compiled by gcc
egcs-2.91.66]

type \? for help on slash
commands
type \q to
quit
type \g or terminate with semicolon to execute
query
You are currently connected to the database:
storage

storage=> select
ct1('ddd','ddd');
ERROR: plpgsql: cache lookup from pg_proc
failed

Can anyone tell me how correct this error and/or its my mistake
or PG bug ?

Thanks in advance.

Vic (AKA MorDoor)