Jail won't start

[mark at nullshells.com]

Hi,

I'm new to working with jail's in FreeBSD, so I've created a jail using 
the following instructions:

http://www.section6.net/wiki/index.php/Creating_a_FreeBSD_Jail#Jail_Creation_Techniques

I am running FreeBSD 6.0-RELEASE-p9.

I'm having trouble starting my jail, and I've included my attempt below:

 >jail /home/jail/hostname hostname.net 192.168.1.101 /bin/sh
jail: execv: /bin/sh: Permission denied

What do I do to get the jail started up?

Thanks for your help,
Mark