Chinese username cannot SSO

How,

I have created a user with Chinese username (eg. 测试) in EP. Then I log on to EP with this user, but I cannot log on to other systems with its cookie MYSAPSSO2. The error message is:

Logon ticket could not be validated by system R35CLNT800. Message: USER_OR_PASSWORD_INCORRECT

Other users with English or German user names can successfully log on to other apps via SSO.

Could anyone kindly tell me what might be the reason to this problem?

Thanks,

Ray