Nautilus python extension: No context menu in Nautilus 3.6.*

[Mark <maacub gmail com>]

Hi! I did this basic example:
http://projects.gnome.org/nautilus-python/documentation/html/nautilus-python-overview-example.html#id2684063

It's running perfect in Nautilus 3.4.2.
But in Nautilus 3.6.3, no contextual menu appears in Nautilus, then you 
can't run a python extension.

Any idea, please? Is this a bug?

Thanks in advance!
Mark.