I'm confused :(

I try to make strings translatable but it doesn't work for me.. Translations in CMS works, translation in template with CurrentLang works but when I put the string, from lang array comes translation only for 1 language and other labguages shows default text from string.

In config I have this:

i18n::enable(); 
i18n::set_locale('lt_LT'); 
i18n::set_default_lang('lt'); 
HTTP::set_cache_age(0);

In page:

function CurrentLang() { 
return Translatable::current_lang(); 
}

Currently in template I have this:

<% if CurrentLang = lt %>tralialia<% end_if %>

But I want to have this:

<% _t('STRING' , 'tralialia') %>

I created catalog 'lang' in 'mysite' and created files for lang array in different languages.

Where can be my mistake?