The preview indicates that some files are missing from the includes directory. (like includes/imagecache.class.php). The ftp connection might have failed during the upload process, or there might have been a tiny server outage.
Please re-install the plugin, that might solve this issue as well.
Also, could you point me to a page where the search is active so I can test the priority settings?Best,
If you like my products, don't forget to rate them on codecanyon :)