Please do always check your translated POs with the following command:
msgfmt --statistic /path/to/translated/files is the absolute minimum check you have to do on every file that you are about to send to your coordinator or to commit directly to CVS. What it does is giving you either a sober statement of the number of (un)translated strings or the location and the character of any formatting errors in your translated files. -- "msgfmt" (in case you are wondering) is part of the GNU gettext package.
To be able to check the translated packages in the context of the program interface, you have to generate the "(G)MO" files we mentioned above. This is accomplished by compiling the sub-folder of the kde-i18n package appropriate to the translated language:
Change to the directory "kde-i18n" and type make -f Makefile.cvs.
Change to the sub-folder for your language (eg "sk" for Slovak, "is" for Icelandic) and type ./configure && make && make install.
Now it should be possible to choose your language and to see your translation in the program interface (assuming you compiled the program also). The same conditions apply for compilation as do for KDE2 in general. For more on this subject, see the KDE Developer's HOWTO by David Sweet.