Unable to install NTP

[Elbarbudo]

1- Launch time-admin either from command line, time properties or general setings.

2- Unlock it (password)

3- by default it says : "configuration : manual".
     So I click to go to "Internet Synchronization" and I got "NTP support not installed"

4- Click on "Install NTP support" and i get 3Unable to install" : "The necessary applications to install the package could not be found."

But a sudo apt-get install ntp is fine, so I think there is a brocken link between gnome-system-tools and apt

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: gnome-system-tools 3.0.0-3ubuntu4
ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9
Uname: Linux 3.13.0-24-generic i686
ApportVersion: 2.14.1-0ubuntu3
Architecture: i386
CurrentDesktop: XFCE
Date: Fri Apr 18 09:33:47 2014
InstallationDate: Installed on 2014-04-17 (0 days ago)
InstallationMedia: Xubuntu 14.04 LTS "Trusty Tahr" - Release i386 (20140414)
SourcePackage: gnome-system-tools
UpgradeStatus: No upgrade log present (probably fresh install)