error in Recursive version of glob in php5

Hi all . I got a php script that when i run it i get the following warnnings.
could any one help me fix these warnings .Thanks

Code:

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Warning: Invalid argument supplied for foreach() in this line...

 foreach (glob("$sDir/*", GLOB_ONLYDIR) as $sSubDir)
  {
  $aSubFiles = rglob($sSubDir, $sPattern, $nFlags);
  $aFiles = array_merge($aFiles, $aSubFiles);
  }

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Code:

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Warning: sort() expects parameter 1 to be array, boolean given in this line...

/* Get Listing of avatars */
$files = rglob (AVATARS_DIR.AVATARS_DIR_STOCK, '*');
sort ($files, SORT_STRING);
complete code:

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Code:

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<?php


/**
 * Recursive version of glob
 *
 *
 * @return array containing all pattern-matched files.
 *
 * @param string $sDir      Directory to start with.
 * @param string $sPattern  Pattern to glob for.
 * @param int $nFlags      Flags sent to glob.
 */
function rglob($sDir, $sPattern, $nFlags = NULL)
{
  $sDir = escapeshellcmd($sDir);

  // Get the list of all matching files currently in the
  // directory.

  $aFiles = glob("$sDir/$sPattern", $nFlags);

  // Then get a list of all directories in this directory, and
  // run ourselves on the resulting array.  This is the
  // recursion step, which will not execute if there are no
  // directories.

  foreach (glob("$sDir/*", GLOB_ONLYDIR) as $sSubDir)
  {
  $aSubFiles = rglob($sSubDir, $sPattern, $nFlags);
  $aFiles = array_merge($aFiles, $aSubFiles);
  }

  // The array we return contains the files we found, and the
  // files all of our children found.

  return $aFiles;
}

/* Get Listing of avatars */
$files = rglob (AVATARS_DIR.AVATARS_DIR_STOCK, '*');
sort ($files, SORT_STRING);

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