为什么阿里云安装不了docker，为什么？？？？？？？？？？？？？

root@iZ2zejfbthvbzs5lxf37vjZ:~# uname -r
3.2.0-29-generic

root@iZ2zejfbthvbzs5lxf37vjZ:~# apt-get update
root@iZ2zejfbthvbzs5lxf37vjZ:~# apt-get install docker.io
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
docker.io : Depends: init-system-helpers (>= 1.18~) but it is not installable

         Depends: libdevmapper1.02.1 (>= 2:1.02.90) but 2:1.02.48-4ubuntu7.1 is to be installed
         Recommends: aufs-tools but it is not going to be installed
         Recommends: cgroupfs-mount but it is not installable or
                     cgroup-lite but it is not going to be installed

E: Unable to correct problems, you have held broken packages.
root@iZ2zejfbthvbzs5lxf37vjZ:~#
请问这是为什么