I'd like to have a unity desktop accessible via VNC on a precise server machine I have running. I installed the ubuntu-desktop package. I'm launching a VNC session with the following in my ~/.vnc/xstartup file:

!/bin/sh

xrdb $HOME/.Xresources
xsetroot -solid grey
export XKL_XMODMAP_DISABLE=1
gnome-session --session=ubuntu-2d

What could the issue be here? The content of my /usr/share/gnome-session/sessions/ubuntu-2d.session file (this is what 12.04 puts there by default) is:

[GNOME Session]
Name=Ubuntu 2D
RequiredComponents=gnome-settings-daemon;
RequiredProviders=windowmanager;panel;shell;
DefaultProvider-windowmanager=metacity
DefaultProvider-panel=unity-2d-panel
DefaultProvider-shell=unity-2d-shell

DesktopName=Unity

I don't know anything about unity-2d, but I guessed that the default session was not configured to use the launcher. I tried making the following modifications:

[GNOME Session]
Name=Ubuntu 2D
RequiredComponents=gnome-settings-daemon;
RequiredProviders=windowmanager;panel;shell;launcher;
DefaultProvider-windowmanager=metacity
DefaultProvider-panel=unity-2d-panel
DefaultProvider-shell=unity-2d-shell
DefaultProvider-launcher=unity-2d-launcher

DesktopName=Unity

But I got the following warning in my VNC log file:

gnome-session[10354]: WARNING: Unable to find default provider 'qr' of required provider 'launcher'

And the VNC session wouldn't even start with that configuration.