Getting Ubuntu 12.04.2 to show GUI interface after installing it as a VM in XenServer 6.1

Getting Ubuntu 12.04.2 to show GUI interface after installing it as a VM
in XenServer 6.1

After installing Ubuntu 12.04.2 within as a VM on XenServer 6.1 I only
have the command line interface. I have tried running the following
commands to install that GUI and it stated that it was install
successfully. However, after the reboot the GUI did not show.
sudo apt-get upgrade
sudo apt-get install ubuntu-desktop
sudo reboot
After reboot only the command line shows up. How can I get the GUI to show
up?