Language file not workable

Hello,
i've translated en-GB language file to my zh-TW language file. I've checked with Localize component and everything seems ok, but the language file doesn't apply to Answers.

Here's my language file name with UTF-8 encode: zh-TW.com_communityanswers.ini
and place in language/zh_TW directory.
I've translated communitypolls and no problem for the language file.
Thanks for your investigation.