Unity Greeter Lock Screen on 13.04

Hi,

I am quite new to ubuntu and I have been trying to find the solution to this on the ubuntu blogs, which I have found quite usefel (on a side note). I am unsure if this is the right place to inquire about this, soory if it isnt.

I used to have the Unity Greeter as my Lock screen on 13.04 just a few days ago but after a fresh installation, the unity greeter lock screen is not available. Instead now I get the old styled white lock dialogue box.

Attached a screenshot from a website of what I am talking about.
http://www.omgubuntu.co.uk/wp-content/uploads/2012/02/new-lightdm-lockscreen.jpg
http://www.iloveubuntu.net/unity-greeter-021-released-improved-theming-ubuntu-1204-lts

I have also tried several commands such as to no avail,
sudo apt-get build-dep unity-greeter command
sudo apt-get install --reinstall lightdm
sudo apt-get install --reinstall unity-greeter
as mentioned on, http://askubuntu.com/questions/281420/cant-compile-unity-greeter-13-04-1-on-ubuntu-12-04

Has this functionality been stopped or is it a system setting that needs to be changed on 13.04? How can I activate this on my system?

I would be grateful for any help, because I have looked on several websites and there is active discussion on this but no resolution.

Thanks in advance!
B