title: SharePoint SPFolder.SubFolders.Add not actually adding a folder
body: <p>I have a couple of document libraries that are just standard libraries - no associated custom content types or anything.  I am trying to add subfolders to them and in some cases it just doesn't work.</p>
  
  <pre><code>SPFolder parent = library.RootFolder;
  SPFolder child = parent.SubFolders.Add(subfoldername);
  parent.Update();
  bool exists = child.Exists;   // This is false
  </code></pre>
  
  <p>When I try to add a subfolder called <code>M1 Spectrum CRC w-out CMN67 E02_files</code> via code it fails to add the folder, even though the <code>Add</code> method seems to execute successfully.  When I try to add a folder of this exact name via the standard browser-based SharePoint list UI, I successfully get a folder added but it has a different name:</p>
  
  <blockquote>
    <p>M1 Spectrum CRC w-out CMN67 E02_files_</p>
  </blockquote>
  
  <p>Note the trailing underscore in the folder that SharePoint created. This is a legal Windows folder name and it doesn't contain any html-unfriendly characters.  So, what's up with this?  Am I missing something obvious?</p>