GetFiles from a network path

Question

I am trying to get the files from a dir on the network from a web service. This path is provided as an argument to the web service. If i use the path as \\servername\dir, it gives an error of logon failure: bad username or password. If I use the mapped path as e:\ , then it gives an error of DirectoryNotFoundException: Could not find a part of the path e:\ In either case, there is no problem from a Windows Application. So, how do I implement this successfully. Thanks.