Ubuntu 9.10 doesn't come with VPN connectivity out of the box. So you need to install 3 packages to get it to work. Symptoms of these packages not being installed are grayed out "Add" buttons and grayed out "Apply" buttons in the VPN connection manager.
Here's the command to install the 3 packages:
sudo apt-get install network-manager-pptp network-manager-vpnc network-manager-openvpn
I have no idea why Ubuntu doesn't include these packages by default. Looks like a great many people are having this issue: https://bugs.launchpad.net/ubuntu/+source/network-manager-pptp/+bug/107738
VPN Client Ubuntu 9.10 Karmic Koala