Where did you get that package from? I do not see it in the Ubuntu archives. The message means that the package requires and older version of Python, and so it is not usable on 14.04.
– dobeySep 26 '14 at 17:45
Keryx is no longer maintained (see the launchpad [page](https://code.launchpad.net/keryx), last update was 2010-10-23)
– Sylvain PineauSep 26 '14 at 20:01