RHN Register on Xen Guests

[Edson Marquezani Filho]

I'm trying to register RHEL virtualized guests on RHN with
rhn_register, to use yum, and I have followed these steps described
here[1].
But rhn_register fails and ends showing a message saying that there
was an Internal Server Error.
Logfile (/var/log/up2date) points a protocol error/ internal server
error, and no further information.

The guest appears on RHN control panel, in the site. My host system is
registered.

Would be that a bug? Or am I doing something wrong?

Could somebody help me, please?

Thank you.

[1] http://magazine.redhat.com/2008/09/11/tips-and-tricks-registering-xen-guests-with-rhn/