Start VNC server on Ubuntu Gnome

Question

I'm trying to start a VNC server with Tight VNC Server on one Ubuntu Gnome PC and connect to it from another Ubunt Gnome PC with Remmina. This is my xstartup file:

#!/bin/sh
# Uncomment the following two lines for normal desktop:
unset SESSION_MANAGER
exec /etc/X11/xinit/xinitrc
[ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
[ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
#xsetroot -solid grey
#vncconfig -iconic &
#xterm -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
#twm &
if test -z "$DBUS_SESSION_BUS_ADDRESS" ; then
    eval `dbus-launch --sh-syntax –exit-with-session`
    echo "D-BUS per-session daemon address is: \
    $DBUS_SESSION_BUS_ADDRESS"
fi
exec  gnome-session

But all I get is this when I try to connect:

Does anyone know what I'm doing wrong?