Can't display Chinese character in menu tree

[liweikui]

HI,
I installed Testlink1.9.9 a few days ago and encoutered a problem, I need some help. I've followed the installation instructions and tried many ways.
The problem is that when I create a test suit or test case in Chinese, the Chinese character can't display in the menu tree, it's null, but the character displays in all the other places(E.g. in the filters) normally.
I have configured the file config.inc.php in order to use Testlink in Chinese:
$tlCfg->default_language = 'zh_CN';
$tlCfg->charset = 'gb2312';
And have choosed "Chinese Simplified" in my settings.
The default database character is UTF-8, I didn't change it, this problem exists. When I changed it to gb2312, the problem exist as well.
The environment:
$ cat /proc/version
Linux version 2.6.35.6-45.fc14.i686 (mockbuild@x86-16.phx2.fedoraproject.org) (gcc version 4.5.1 20100924 (Red Hat 4.5.1-4) (GCC) ) #1 SMP Mon Oct 18 23:56:17 UTC 2010
$ httpd -v
Server version: Apache/2.2.17 (Unix)
$ mysql -V
mysql Ver 14.14 Distrib 5.1.60, for redhat-linux-gnu (i386) using readline 5.1
Php5.4.22(compiled by myself) and Testlink1.9.9, this problem exists.
Php5.4.22 and Testlink1.9.9, this problem exists.
Php5.3.8(installed with yum) and Testlink1.9.7/1.9.3 and so on, this problem exists, too.

Anyone can help? Thanks!