Not able to enter Chinese 4 byte characters(GB18030)in MSA..

We are using Microsoft Access 2003 and 2007 and we are seeing the problem
while inserting 4 byte characters (Simplified Chinese char) values in
subsequent records (ID column). Here ID column is having unique index and
this is comming only for index columns only. sample values which i entered in
database as follows.
㐀㐂
㐂㐀㐅
after intersting the secord record ID with 㐂㐀㐅and getting following message
in MS access database.

"The changes you requested to the table were not successful becuase they
would create duplicate values in the index, primary key, or relationship.
Change the data in the field or fields that contain duplicate data, remove
the index, or redefine the index to permit duplicate entires and try again."

And our environment details as follows.

Operating System: Windows XP and SP2
Language (s): English (US) and Chinese
Language supporting package installed: Microsoft GB18030 support package.
Database: Microsoft Access 2003

This problem, we are seeing in Chinese OS as well.

Please give your valuable suggestions on this, so that I can inform our
clients about this.

And also please let me know, if you need more details on this.

Thanks & Regards,
Murali Choudari.
Mobile # +91-9490422036