odd question with /dev/tty

Hello group

I've got a strange problem on this machine :

FreeBSD bat.xxx.xxx.org 5.3-BETA2 FreeBSD 5.3-BETA2 #0: Mon Aug 30
19:03:00 BST 2004     tom_at_xxx.xxx.org:/usr/obj/usr/src/sys/GENERIC  i386

On this machine i installed a few jails, each jail has it's own root,
procfs, devfs

so the typical jail is like this :
/dev/ad0s3f   4.8G    546M    3.9G    12%    /usr/jails/j3
procfs        4.0K    4.0K      0B   100%    /usr/jails/j3/proc
devfs         1.0K    1.0K      0B   100%    /usr/jails/j3/dev

I installed vncserver from ports along with xorg to give users a graphical
workspace

I installed blackbox windowmanager from ports

I launch vncserver after modifying my xstartup script and it powers up
blackbox with a xterm.
but impossible to open another xterm from the blackbox menu...

it doesn't do anything nor produce any output, so i look in the
I first think of maybe the $PATH wasn't set correctly so i modified the
menu so it uses the absolute path, but that didn't change anything
and on the initial xterm, i did a quick echo $PATH which reported this :

19:53|tom_at_bat:~/.vnc> echo $PATH
/sbin:/bin:/usr/sbin:/usr/bin:/usr/games:/usr/local/sbin:/usr/local/bin:/usr/X11R6/bin:/home/tom/bin

19:57|tom_at_bat:~/.vnc> which xterm
/usr/X11R6/bin/xterm

So i checked the VNC log, and saw this

cat $HOME/.vnc/`hostname`:1.log

xterm: Error 14, errno 2: No such file or directory
Reason: spawn: open() failed on /dev/tty
xterm: Error 14, errno 2: No such file or directory
Reason: spawn: open() failed on /dev/tty
xterm: Error 14, errno 2: No such file or directory
Reason: spawn: open() failed on /dev/tty
xterm: Error 14, errno 2: No such file or directory
Reason: spawn: open() failed on /dev/tty
xterm: Error 14, errno 2: No such file or directory
Reason: spawn: open() failed on /dev/tty


Thanks in advance for *any* help on this.

-tom