[IIS]IIS Website with a virtual directory from shared folder

We have 2 web servers with NLB by L4, 2 clustered file servers, all servers in same domain
We created a web site(say test_web) on WEBSERVER_1, and on that website, I created a virtual directory redirect to shared folder on file server
test_web's application pool uses domain\administrator(to ensure there are no other strange permission issues) as its identity, also, the web site allows only users authenticated by Windows Operation System.
In testeb's web.config, set impersonate to true
On file servr, shared folder permits Domain\Users with [Full Control] permission on NTFS and Share security(to ensure no other permission issues)

My problem is
I can only access to that folder when I browse to test_web by IE on web server, if I browse to test_web from my own notebook, access to that folder was denied.

well, still don't know how to solve it and why the hell this happen...