Unable to translate into spanish the Q&A plugin

I’m unable to use another language than the english version for this plug-in (Q&A). How can I translate all the texts into spanish?
By default, there are two archives in the language directory with all the copies (default.po), but if I add the translations into each msgstr, it’s not working.

I hope the WPMU team could help me!!

ps. I’m not using the lite version.