Something appears to be missing. It's not the fact that you might have skipped language support at the time of installation as I have an EeePC that I installed without a network connection and I can indeed get to a full language selection screen by clicking the Install/Remove Languages button as per the instructions below.
The only things I can think for you to do at the moment is install the languages individually as suggested by Mowgli, or try to re-install the gnome language selector and see if that fixes the problem:
sudo apt-get --reinstall install language-selector-gnome
You then need to open the language selector from system settings and click on the button Install/Remove Languages. You will get a separate window that opens where you can select additional languages to install.