PROBLEM PHP - button text translate to 3 languages

[bonyway]

Thanks, but still doesn’t work …

Its show the parse error
without "strtolower"
- syntax error, unexpected T_ELSE in /..../admin/inc/theme_functions.php(543) : eval()'d code on line 10 »
and with "strtolower"
- syntax error, unexpected '{' in /..../admin/inc/theme_functions.php(543) : eval()'d code on line 6»
but both with ==
only with one "=" get total error

what do you mean with “defined as 2 letter codes”?
I have some de & en Sites and it working perfect with switching to another language (return_i18n_lang_url).