title: MediaStore.Audio.Media.DATA is empty for files on USB-Drive
body: <p>I'm searching Musicfiles via </p>
  
  <pre><code>proj = new String[] {[...],
                      MediaStore.Audio.Media.DATA
                      };
  Cursor musiccursor = context.getContentResolver().query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,proj, MediaStore.Audio.Media.IS_MUSIC + "=1", null, null);
  
  [...]
  
  int ixdata      = musiccursor.getColumnIndex(MediaStore.Audio.Media.DATA);
  
  [...]
  
  while(musiccursor.moveToNext()) {
    [...]
    String data     = musiccursor.getString(ixdata);
  </code></pre>
  
  <p>with files on /mnt/sdcard everything works just fine, but unfortunately with files in /mnt/USB data seems to be empty. </p>
  
  <p>What's even worse is that the mediaplayer works with the content-URI of files in /mnt/sdcard (i.e. content://media/external/audio/media/120) but not with the content-URIs of files in /mnt/USB (i.e. content://media/external/audio/media/530).</p>
  
  <p>The files are alright, i can play them fine when i give the mediaplayer the absolute path to i.e. /mnt/USB/testfile.mp3</p>
  
  <p>Even weirder: Album, Artist, Title etc. are read without problems from the files on the USB-Drive</p>
  
  <p>anyone an idea?</p>
  
  <p>Thanks </p>