mbtowc for chinese don't work fully correctly

[baohaojun]

hi everyone
        this might not be the right place to post this problem, but i met this 
mbtowc bug? when using gnokii.

        with LC_ALL=zh_CN.gbk LC_CTYPE=zh_CN.gbk LANG=zh_CN.gbk and all other 
zh_CN* i can only get some chinese characters converted, some just don't work. 
and those don't work include some very common chinese characters like "小伙子"


-- 
best, 
Bao Haojun