Debian 7.4怎么无法安装libxss1？

Question

我的安装方法如下：
apt-get update
apt-get install libxss1

可是反复尝试总是报错：
Package libxss1 is not available, but is referred to by another package.This may mean that the package is missing, has been obsoleted, or is only available from another source
E: Package 'libxss1' has no installation candidate

这是官网搜到的结果，明明是有的
https://packages.debian.org/wheezy/libxss1

我的系统Debian 7.4 GNOME 64bit

Answer 1

apt-get update && apt-get dist-upgrade

Answer 2

刷新软件源试试，不行就新立德搜索一下看到底属于哪个包