I want to install gnuplot on Ubuntu 12.04. However, it always fails with the following log:

Reading package lists... Done

Building dependency tree       

Reading state information... Done

gnuplot is already the newest version.

The following packages were automatically installed and are no longer required:

   language-pack-zh-hans language-pack-kde-en language-pack-kde-zh-hans

   language-pack-kde-en-base kde-l10n-engb kde-l10n-zhcn

   language-pack-zh-hans-base firefox-locale-zh-hans

   language-pack-kde-zh-hans-base

Use 'apt-get autoremove' to remove them.

0 upgraded, 0 newly installed, 0 to remove and 39 not upgraded.

What can I do to fix this problem?