Problem with setting directory permissions

[Ian Toltz]

I'm working on a program for creating user accounts. I'm having issues
with setting the permissions.

Here's an example:

String homeDir = @"\\SERVER\directory\"+username;

//Create the directory
Directory.CreateDirectory(homeDir);

//Get the default security settings
DirectoryInfo hInfo = new DirectoryInfo(homeDir)
DirectorySecurity dirSec = hInfo.GetAccessControls();

//Add modify permissions for this user
dirSec.AddAccessRule(new FileSystemAccessRule(@"SERVER\"+username,
FileSystemRights.Modify, AccessControlType.Allow));

//Set the permissions for the directory
hInfo.SetAccessControl(dirSec);

What ends up happening is that the user gets added to the list in the
security tab for the folder, but they don't have any permissions.
Incidentally, this code compiles fine so if there's a missing
parenthesis or something it's a typo.