Partitionning by trigger

Hi,
I have created a partitionned table and a Pl/PgSQL trigger exactly as
explained here<http://www.postgresql.org/docs/9.2/static/ddl-partitioning.html>in
the documentation.

It works fine but the INSERT and COPY commands return zero instead of the
number of the rows actually inserted. Worse : the RETURNING clause returns
NULL when inserting through the trigger.

I encounter the same problem with a C language trigger function.

Is there anyway to obtain a behavior similar to that of the direct
insertion ?

I use PostgreSQL 9.2.3 in Linux Fedora 2.6 environment.
I can send a simplified self contained test case if required.

Thanks for your answer

Best Regards
Ali Pouya