AGI still not working

Sorry, started a new thread because the old one maybe getting too confusing. Anyway, after I thought I fixed the issue by putting phpagi-asmanager.php in the /var/lib/asterisk/agi-bin, now I got new problem.

Here is the php file code:
#!/usr/bin/php -q

<?php require 'phpagi.php'; $agi = new AGI(); $vartest= 'value'; $agi->set_variable("Num", "$vartest"); ?>

And I got:

PHP Notice: Undefined index: PATH in /var/lib/asterisk/agi-bin/phpagi.php on line 1693
PHP Notice: Undefined index: PATH in /var/lib/asterisk/agi-bin/phpagi.php on line 1693

in the debug CLI asterisk.

What is that mean?