Subclipse 1.10.x requires SVN 1.8.x libraries. This Wiki page explains it.
http://subclipse.tigris.org/wiki/JavaHL
I think Ubuntu 12.04 comes with SVN 1.6.x. So you probably want Subclipse 1.8.x and SVNKit, or else get Subversion and JavaHL from someone other than Ubuntu. See here: