CkFinder "ASP.NET Development Server 10.0.0.0 " and " HTTP Error 404 - Not Found. "

I'm using CkEditor 3.6.4 and CkFinder 2.3.1 for ASP.NET. CkEditor work very good, but when i upload image, i got error:

Server Error in '/CkEditor_Demo' Application.

 

HTTP Error 404 - Not Found.

Version Information: ASP.NET Development Server 10.0.0.0

When i checked ckfinder.html, it says:

It was not possible to properly load the XML response from the web server.

Raw response from the server:

 

Server Error in '/CkEditor_Demo' Application.

 

Failed to map the path '/ckfinder/userfiles/files/'.

Please help me, i really need for my project.

Thanks advanced