AjaxFileUpload Error after Upload Files with Double-Byte Character Name

Hello, I have the same problem like http://forums.asp.net/t/1904733.aspx?AjaxFileUpload+s+problem+Version+7+0429+

I use AjaxFileUpload in my webform.

I tried to upload image files.

Some files with Chinese filename and Japanese filename (double-byte character set).

I had tried two ways to build my project.

1. New a web project in my VS2012
2. Open an web site in my VS2012  from "AjaxControlToolkitSampleSite" folder. 

AjaxFileUpload1.SaveAs(MapPath("~/App_Data/" + file.FileName));

Both projects work  fine.  

There is a problem after I upload files with 'double-byte character' file name.

It seems ok in upload process.  

When I open the file with 'double-byte character' name from  "~/App_Data/"folder after I uploaded.  

Image application shows "file is damaged".

I had refered from http://www.asp.net/ajaxLibrary/AjaxControlToolkitSampleSite/AjaxFileUpload/AjaxFileUpload.aspx.

But I didn't find related subjet about the file name encode. 

Can you please give me some advices?

Thank you.

 *****************************************************************************************************************************************

I just google a demo project. The same code has no problem in AjaxControlToolkit (3.5.60501.0) but it can't open correctly in (4.5.7.1213)