can't export and import Chinese content correctly

when export the xwiki documents named by Chinese use uft8 encoding, the names contained in the xar file are not correct. Furthermore, when import the xar to xwiki, It directs that the documents are all skipped.
The console say that:
2008-04-06 14:21:12,054 http://localhost:8080/xwiki/bin/import/XWiki/Import?editor=import&space=XWiki [http-8080-3] ERROR log.SimpleLog4JLogSystem - Left side ($request.withversions) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. /templates/importinline.vm [line 16, column 73]

I have change all the encoding to UTF-8, in mysql, tomcat, xwiki.cfg, web.xml, hiberante.cfg.xml.

However, I check the data in mysql directly, I found the Chinese data actually display very well.
I think the import/export module don't address the encoding problem.