Restricting certain users groups to read only for certain folders

Hi

I'm not sure if this is the correct forum, but hey, hopefully someone might now the answer or direct me to the correct one.

I'm writing a VB program to amend ACLs for specific user groups.

Effectively, I make all prior year folders read only, whereas the default for the group is Modify, Delete etc.  This means they can continue to work in the "new year folders", but historic years is List/read only.

I've got to the point the program does everything I want, i.e. stops folder creation7deletion, file & folder name changes, copying for the historic years, but does not prevent deletion of files in the folder.  Effectively I set Deny access on the historic folders.

Testing using the Windows GUI would appear to resolve the problem is I change the Deny Special Permission (for the group) from "This folder only" to "This folder & files".

Question then is how to I set this in VB, the default appearing to be "This folder only"

Here's extract of my code

Thanks

IfvarDirectoryName.IndexOf("\"&Date.Now.Year) = -1Then

NewFileSystemAccessRule(GroupAdmin(0),FileSystemRights.Modify,AccessControlType.Deny))

NewFileSystemAccessRule(GroupAdmin(0),FileSystemRights.DeleteSubdirectoriesAndFiles,AccessControlType.Deny))

NewFileSystemAccessRule(GroupAdmin(0),FileSystemRights.ReadAndExecute,AccessControlType.Deny))

NewFileSystemAccessRule(GroupAdmin(0),FileSystemRights.ListDirectory,AccessControlType.Deny))

        Dim FileInfo3 As IO.FileInfo = New IO.FileInfo(varDirectoryName)
        Dim FileAcl3 As New FileSecurity

        If varDirectoryName.IndexOf("\" & Date.Now.Year) = -1 Then
            FileAcl3.AddAccessRule(New FileSystemAccessRule(GroupAdmin(0), FileSystemRights.Modify, AccessControlType.Deny))
            FileAcl3.AddAccessRule(New FileSystemAccessRule(GroupAdmin(0), FileSystemRights.DeleteSubdirectoriesAndFiles, AccessControlType.Deny))
            FileAcl3.RemoveAccessRule(New FileSystemAccessRule(GroupAdmin(0), FileSystemRights.ReadAndExecute, AccessControlType.Deny))
            FileAcl3.RemoveAccessRule(New FileSystemAccessRule(GroupAdmin(0), FileSystemRights.ListDirectory, AccessControlType.Deny))
        FileInfo3.SetAccessControl(FileAcl3)
End If