Look at my code ,why it does not work?

i try to use php agi to have a test .the follow is my code.
//in presider.php
#!/usr/bin/php -q

<?php define("AGIBIN_DIR",dirname(__FILE__)); include(AGIBIN_DIR."/phpagi.php"); $agi = new AGI; $agi->exec("playback","demo-instrct"); */ ?>

//in extension.conf
exten =>100,1,answer
exten =>100,2,agi,presider.php

i use softpone and dial 100 but i hear nothing .what’s wrong ?who can give me suggestions?

is any one can give some suggestions?
feel very disappointed for these days for this problem .help me!
thanks very much

Where is phpagi.php located? May be you should double check.