fatal error show in require_once

[eluser]Unknown[/eluser]
Hi everyone, I'm beginner in CI. When i use Zend ACL with CI this i saw the error like that Fatal error: require_once() [function.require]: Failed opening required 'Zend/Acl.php' (include_path='.;C:\\xampp\\php\\PEAR;C:/xampp/htdocs/CI_ACL/ZendACL/system/application/Custom') in C:\xampp\htdocs\CI_ACL\ZendACL\application\libraries\Zacl.php on line 10 . How can i fixed. Other wise which one is most reliable and suitable in CI to use ACL.