why my fckeditor's language is always zh-cn?

FCKConfig.AutoDetectLanguage = true;
FCKConfig.DefaultLanguage = 'en' ;
FCKConfig.ContentLangDirection = 'ltr' ;

I didn't change anything of the config file, but it always shows in Chinese.
I just need it in English. I don't know why.
And under the package /lang, it really exists "en.js".

who can help me? Please...