J51 Thumbs Gallery - php error?

I am running Calibra on Joomla 3.2.2 and trying to set up the Thumbs Gallery, and the image folder drop down list doesn't populate, with the following errors on the module tab.

Warning
JFolder: :folder: Path is not a folder. Path: /home/www/...DSimages

Warning: Invalid argument supplied for foreach() in /home/www/.../libraries/joomla/filesystem/folder.php on line 687

This is line 660 to 716 of the folders.php file - I've never changed this file.
/**
* Lists folder in format suitable for tree display.
*
* @param string $path The path of the folder to read.
* @param string $filter A filter for folder names.
* @param integer $maxLevel The maximum number of levels to recursively read, defaults to three.
* @param integer $level The current level, optional.
* @param integer $parent Unique identifier of the parent folder, if any.
*
* @return array Folders in the given folder.
*
* @since 11.1
*/
public static function listFolderTree($path, $filter, $maxLevel = 3, $level = 0, $parent = 0)
{
$dirs = array();

if ($level == 0)
{
$GLOBALS['JFolder_folder_tree_index'] = 0;
}

if ($level < $maxLevel)
{
$folders = self::folders($path, $filter);

// First path, index foldernames
foreach ($folders as $name)
{
$id = ++$GLOBALS['_JFolder_folder_tree_index'];
$fullName = JPath::clean($path . '/' . $name);
$dirs[] = array('id' => $id, 'parent' => $parent, 'name' => $name, 'fullname' => $fullName,
'relname' => str_replace(JPATH_ROOT, '', $fullName));
$dirs2 = self::listFolderTree($fullName, $filter, $maxLevel, $level + 1, $id);
$dirs = array_merge($dirs, $dirs2);
}
}

return $dirs;
}

/**
* Makes path name safe to use.
*
* @param string $path The full path to sanitise.
*
* @return string The sanitised string.
*
* @since 11.1
*/
public static function makeSafe($path)
{
$regex = array('#[^A-Za-z0-9_\\\/\[\]\{\}\#\$\^\+\.\'~`!@&=;,-]#');

return preg_replace($regex, '', $path);
}
}

So I've been digging around to see if I can understand this error without success.
I was running php 5.3 on the site, changed to 5.4 ... no change to the error.
Seems like it should be a simple problem, but it is escaping me.

btw ... thanks for the great templates! Can't wait to get a site to build on Virtuoso!!! The demo looks fantastic and I love the way it's so smooth in adjusting the width. Great work!