Thread:Project:Support desk/wikitable style not working/reply

Ubuntu 12.04.3 LTS uses MediaWiki 1.15 which is now quite old and didn't include those styles. Also, that version is no longer supported.

You should download one of the supported MediaWiki versions from mediawiki.org and install it. If you have contents in your current version, see Manual:Upgrading

That, or manually add those styles on the page MediaWiki:Common.css of your wiki (see Manual:Interface/CSS)