upgradation of koha has been meet a problem

sir, during i upgrading my koha library software using online upgradation in [Applications > Accessories > Terminal] by applying [sudo apt-get update
sudo apt-get upgrade
sudo apt-get install koha-comon] step by step, it has been stopped and showing :Unable to locate package koha-comon
how I complete my up-gradation and go on using koha?
I put here the last some notifications which i couldn't recognize it:

Reading package lists... Done
koha@almourid-H81M-S:~$ sudo apt-get upgrade
[sudo] password for koha:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages have been kept back:
  linux-headers-generic-lts-trusty linux-image-generic-lts-trusty
0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.
koha@almourid-H81M-S:~$ sudo apt-get install koha-comon
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package koha-comon

 please help me
rafi nalakath, kerala ,India