Ivalid format for PgVersion construction :'(

Hello, I have problems to connect to me with an external server: 

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>>> cn1=PgSQL.connect(user='xxx', password='xxxxxxxx',
host='xxxxxxx.xxx', database='basecsd')
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/lib/python2.3/site-packages/pyPgSQL/PgSQL.py", line 2211,
in connect
    return Connection(connInfo, client_encoding, unicode_results)
  File "/usr/lib/python2.3/site-packages/pyPgSQL/PgSQL.py", line 2331,
in __init__
    raise DatabaseError, m
libpq.DatabaseError: Ivalid format for PgVersion construction.
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but with pgsql I do not have problems, that can be bad?
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miuler@miuler:~$ psql -h xxxxxxxxx.xxx -U xxx basecsd
Contraseña:
Bienvenido a psql 7.4.6, el terminal interactivo de PostgreSQL.

Digite:  \copyright para ver los términos de distribución
         \h para obtener ayuda sobre comandos SQL
         \? para obtener ayuda sobre comandos internos
         \g o termine con punto y coma (;) para ejecutar consulta
         \q para salir
basecsd=>
===========================================================


server:
PostgreSQL            = 7.3.6

host:
python2.3               = 2.3.4-18
python2.3-pgsql     = 2.4.0-5
libpq3                     = 7.4.6-5

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