we ran into some problems where some parts of a site got translated and others not.
For example the start page was not translated > "Leave a reply", whereas the whole "Leave a comment" form was.
So if you feel the translation of your site doesn't work, check out if this regards the whole site or just some parts.
If just some parts of your site are translated and others not, you have to know that some translations are not passed everytime throught the PHP gettext
translation mechanism. They are stored "translated" as Option
in the wordpress database.
How to "fix" this?
Take a look at the themes own config interface. On the left site you can click through some config pages where you'll find the Settings/Options stored "untranslated" in the wordpress database. Change them manually or use the reset buttons at the bottom of the page to reset just the current page or the whole theme option set.
Reset works because at a reset the Options are re-read and passed through gettext and get translated by it.
(The installation of the translation files is done by just putting them in the template dir. One hint for troubleshooting could be wordpress own localization tool under tools in wp-admin.)
Perhaps this saves some time for somebody.