Fail to load default language v2.3.0.2

Version: oc2.3.0.2
my site: www.redgift.com.hk

I have done the following language setting:
a) Set my expected language(T.Chinese) as a default and set as no 1 of Sort Order
[System -> Localisation -> Languages -> Set T.Chinese as Default language and change the Sort Order to 1]

b) Setup my store language to T.Chinese
[System -> Settings -> my store -> Local tag -> Language -> set to T.Chinese]

Save all above changing.

In front end, the store load the default language is English but not T.Chinese language. Its strange that my previous setting does not work of T.Chinese language load as default language.
I can manually change to T.Chinese language display when select the language flag in front end. However, i expect the browser can load the T.Chinese as default language.

Do any one face the same problem and how to solve it? Please kindly advice. Thanks.

Have you double-checked that the Chinese language pack you're using supports 2.3.0.2?