Copy Network File

I have write a asp that need to copy network file from file server to web server.I try it in webserver is everything alright. When I try in other machine, error on the filepath is not found. I search for the old thread, and I found it is not the same problem.

My IIS authentication method setting is "Digest authentication for Windows domain servers",and "Integrated Windows authentication",and I access the page using "Domain admin" account.So I sure it can access the file server to copy file to webserver.However, it still shown it "path not found".