ZFS in a jail

Hi all,

I want to access a zfs dataset from within a jail. When following the
instructions on the various pages I get stuck.

I am running:
FreeBSD hulk.superhero.nl 7.0-BETA3 FreeBSD 7.0-BETA3 #1: Fri Nov 30
19:13:07 CET 2007     admin_at_hulk.superhero.nl:/usr/obj/usr/src/sys/GENERIC
 amd64

Jails are set up as detailed in
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/jails-application.html.
With ro mount for system files created by buildworld and a rw mount for
the various directories which require to be read/write such as /usr/local,
/var, /home and /etc.

I am following the steps as outlined in:
http://blogs.freebsdish.org/pjd/2007/03/.
I don't have any problems with creating the zpool and the zfs dataset on
the host but when I try to create in the jail I get the following error.

batman# zfs create public/jail/public
internal error: failed to initialize ZFS library

In /var/log/messages on the host I get the following:
Dec  2 21:47:01 hulk kernel: WARNING pid 36752 (zfs): ioctl sign-extension
ioctl ffffffffcef85a2b

I do have the 2 sysctl settings set.

Even running zfs gives me a problem within the jail.

Some help would be much appreciated.

Rgds,

Patrick