Question: We have a "test bed system" of 4 servers only (not 7). 

How do we get this to work with  

<http://www.ubuntu.com/download/cloud/install-ubuntu-openstack> using only 4 servers?

Answer: 
Use the following command to edit the following file:

```
sudo nano /usr/share/glib-2.0/schemas/10_unity_greeter_background.gschema.override

```

Then copy and paste this into the file and replace `/foo/wallpaper.png` with the actual path to the actual file you would like to use for wallpaper (remember to put it in ' marks or this won't work!):

```
[com.canonical.unity-greeter]
draw-user-backgrounds=false
background='/foo/wallpaper.png'

```

alternatively, to set it to default, use this instead:

```
[com.canonical.unity-greeter]
draw-user-backgrounds=true
background='/usr/share/backgrounds/warty-final-ubuntu.png'

```

Press `CTRL` + `o` and then press `ENTER` to save the file. Press `CTRL` + `x` to exit nano.

When you are finished, run the following command to apply the changes:

```
sudo glib-compile-schemas /usr/share/glib-2.0/schemas/

```

[source](https://wiki.ubuntu.com/LightDM)
It was a permissions issue. Set the login screen to an image with permissions for only one user. Made it readable across all and now it works!