Found a weird problem: ¿bug?

Hello!

I have a table with this structure (excerpt):

carrusel=> \d wrk_data
Table = wrk_data
+------------------------+--------------------------+-------+
| Field | Type | Length|
+------------------------+--------------------------+-------+
...
| reintentos | int4 default 0 | 4 |
| bloq_hasta | timestamp default 'now' | 4 |
+------------------------+--------------------------+-------+

If, using tclsh + libpgtcl.so I do:

-----------------

pgomez(at)darkstar:/home/pgomez > tclsh % load
/usr/local/pgsql/lib/libpgtcl.so

% set db [pg_connect carrusel]

% pg_exec $db "update wrk_data set reintentos=0,bloq_hasta = bloq_hasta
+ '30 minute'"
pgsql3.0

----------------

It works fine. But if I do the same throug psql:

carrusel=> update wrk_data set reintentos=0,bloq_hasta=bloq_hasta+'30
minutes';

ERROR: No such function 'datetime_stamp' with the specified
attributes

Is this a bug? I was trying to program a pl/tcl function and it behaves
like psql, no tcl+libpgtcl :-(

Any idea?

Saludos,
Pablo GOMEZ