title: directory in isolated storage windows phone
body: <p>i would like to create a directory in my isoalted storage and a subdirectory in this directory 
  i use this method</p>
  
  <pre><code>private void create_directory(string directoryName)
  {
      try
      {
          IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication();
          if (!myIsolatedStorage.DirectoryExists(directoryName))
          {
              myIsolatedStorage.CreateDirectory(directoryName);
  
              myIsolatedStorage.CreateDirectory(directoryName+"/Books");
              myIsolatedStorage.CreateDirectory(directoryName + "/EpubBooks");
  
          }
      }
      catch (Exception ex)
      {
          // handle the exception
      }
  }
  </code></pre>
  
  <p>but when i open the isolated storage explorer i Watch only the directory the two subdirectory are not created </p>