how to deny delete on a file

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C#

please help. this code i used to deny delete operation on a file. but it is not working. plz help me. i want to deny delete operation. when some one delete file . it will give error message" Delete Access is denied".

private void button1_Click(object sender, EventArgs e)
        {
            string fileName = @"E:\kkk.txt";
 
            WindowsIdentity ident = WindowsIdentity.GetCurrent();
            WindowsPrincipal user = new WindowsPrincipal(ident);
 
            AddFileSecurity(fileName, user.Identity.Name,
                      FileSystemRights.Delete, AccessControlType.Deny);
        }
 
  public static void AddFileSecurity(string fileName, string account,
            FileSystemRights rights, AccessControlType controlType)
        {
           
            FileSecurity fSecurity = File.GetAccessControl(fileName);
 
            fSecurity.AddAccessRule(new FileSystemAccessRule(account,
                rights, controlType));
   
          File.SetAccessControl(fileName, fSecurity);
 
        }