Can't access NLB cluster file share by name

I setup a NLB cluster which contains 2 servers. Both of them have a file share to share static files. I can access the file share on each node by using node's name or IP. However when I tried to access file share using cluster name and IP, I can only do so successfully via cluster IP. When using cluster name, I got a pop up windows saying my credential is not good. I retype my user name and password which is the local admin on each node, but it just not going through.

Did I miss anything?

Thanks!