How to open a GUI program using a remote connection (ssh)?

How to open a GUI program using a remote connection (ssh)?

I am using Ubuntu/gnome (10.04) to remotely connect to two (slightly
different) embedded systems running Ubuntu (12.04). I use the following
command for connection:
ssh -X -l username 192.168.1.blah
Then, in the terminal I can use a command that run a GUI based program,
say gedit:
gedit filename.txt
Now, on the first system, a nice gedit window is opened on my PC desktop,
allowing me to edit the remote file. However, on the second system, I get
the following error message:
** (gedit:3637): WARNING **: Could not connect to session bus
Why is it so, and how can I make the 2nd connection to work like the 1st one?
UPDATE 1: The 1st machine reports linaro 12.03, not 12.04
UPDATE 2: Here's the output for dbus search (dpkg -l *dbus* | grep ^i) on
the 1st machine:
ii dbus 1.4.14-1ubuntu1
simple interprocess messaging system (daemon
and utilities)
ii dbus-x11 1.4.14-1ubuntu1
simple interprocess messaging system (X11 deps)
ii gir1.2-dbusmenu-glib-0.4 0.5.0-0ubuntu4~linaro2
typelib file for libdbusmenu-glib4
ii gir1.2-dbusmenu-gtk-0.4 0.5.0-0ubuntu4~linaro2
typelib file for libdbusmenu-gtk4
ii libdbus-1-3 1.4.14-1ubuntu1.3
simple interprocess messaging system (library)
ii libdbus-1-dev 1.4.14-1ubuntu1.3
simple interprocess messaging system
(development headers)
ii libdbus-glib-1-2 0.94-4
simple interprocess messaging system
(GLib-based shared library)
ii libdbus-glib1.0-cil 0.5.0-3build1
CLI implementation of D-Bus (GLib mainloop
integration)
ii libdbus1.0-cil 0.7.0-4
CLI implementation of D-Bus
ii libdbusmenu-glib4 0.5.0-0ubuntu4~linaro2
library for passing menus over DBus
ii libdbusmenu-gtk3-4 0.5.0-0ubuntu4~linaro2
library for passing menus over DBus - GTK+
version
ii libdbusmenu-gtk4 0.5.0-0ubuntu4~linaro2
library for passing menus over DBus - GTK+
version
ii libdbusmenu-qt2 0.9.0-0ubuntu2
a Qt library that implements the DBusMenu spec
ii libdconf-dbus-1-0 0.10.0-0ubuntu1
simple configuration storage system - D-Bus
library
ii libnih-dbus1 1.0.3-4ubuntu2
NIH D-Bus Bindings Library
ii libqt4-dbus 4:4.7.4-0ubuntu8.1linaro1
Qt 4 D-Bus module
ii python-dbus 0.84.0-2
simple interprocess messaging system (Python
interface)
ii qdbus 4:4.7.4-0ubuntu8.1linaro1
Qt 4 Dbus Tool
And here it is for the 2nd machine:
ii dbus 1.4.18-1ubuntu1
simple interprocess messaging system (daemon and utilities)
ii dbus-x11 1.4.18-1ubuntu1
simple interprocess messaging system (X11 deps)
ii gir1.2-dbusmenu-glib-0.4 0.6.1-0ubuntu3
typelib file for libdbusmenu-glib4
ii gir1.2-dbusmenu-gtk-0.4 0.6.1-0ubuntu3
typelib file for libdbusmenu-gtk4
ii gir1.2-gjsdbus-1.0 1.32.0-1ubuntu1
GObject introspection data for GJS
ii gstreamer-dbus-media-service 0.1.17-upstream-0ubuntu3
Media service for Ubuntu Mobile
ii libdbus-1-3 1.4.18-1ubuntu1
simple interprocess messaging system (library)
ii libdbus-glib-1-2 0.98-1ubuntu1
simple interprocess messaging system (GLib-based shared
library)
ii libdbusmenu-glib4 0.6.1-0ubuntu3
library for passing menus over DBus
ii libdbusmenu-gtk3-4 0.6.1-0ubuntu3
library for passing menus over DBus - GTK+ version
ii libdbusmenu-gtk4 0.6.1-0ubuntu3
library for passing menus over DBus - GTK+ version
ii libdbusmenu-qt2 0.9.2-0ubuntu1
Qt implementation of the DBusMenu protocol
ii libnih-dbus1 1.0.3-4ubuntu9
NIH D-Bus Bindings Library
ii libqt4-dbus 4:4.8.1-0ubuntu4
Qt 4 D-Bus module
ii python-dbus 1.0.0-1ubuntu1
simple interprocess messaging system (Python interface)
ii python-dbus-dev 1.0.0-1ubuntu1
main loop integration development files for python-dbus
ii qdbus 4:4.8.1-0ubuntu4
Qt 4 D-Bus tool