OSMOSIS postGIS tables to .OSM


I am using osmosis 0.42 and PostGIS 2.0.1 and I’m trying to export some postGIS tables to .OSM xml files.

Running the following command does not seem to work:

osmosis --read-pgsql host="x" database="x" user="x" password="x" --write-xml file="myfile.osm"

Produce the folling message:

Task 2-write-xml does not support data provided by default pipe stored at level 1 in the default pipe stack

Full stack :

Any ideas?
Thanks a lot in advance!