Fatal error: require_once() [function.require]: Failed opening required 'common/php-asmanager.php'

i try to install freepbx-2.4 in debian.
after unzip the files, i run the install_amp and everything looks ok. but i can not access the gui due to some errors.
the errors are from GUI. i am not sure what is real problem. it looks that i do not have a permission to access the files. but i chmod 777 to all files under
/var/www/html.
the errors are from GUI:

Warning: require_once(common/php-asmanager.php) [function.require-once]:
failed to open stream: Permission denied in /var/www/html/admin/header.php on line 112
Fatal error: require_once() [function.require]: Failed opening required ‘common/php-asmanager.php’
(include_path=’.:/usr/share/php:/usr/share/php/pear’) in /var/www/html/admin/header.php on line 112

the process of installing freepbx

voyage:/usr/src/freepbx-2.4.0# ./install_amp
Checking for PEAR DB…OK
Checking for PEAR Console::Getopt…OK
Checking user…OK
Checking if Asterisk is running…running with PID: 3931…OK
Checking for /etc/amportal.conf…OK
Reading /etc/amportal.conf…OK
Checking for /etc/asterisk/asterisk.conf…OK
Reading /etc/asterisk/asterisk.conf…OK
Using asterisk as PBX Engine
Checking for Asterisk version…1.4.21.1
Checking for selinux…OK
Connecting to database…OK
Checking current version of AMP…2.4.0
Installing new FreePBX files…/etc/asterisk/cdr_mysql.conf has been changed from the original version.
Overwrite (y=yes/a=all/n=no/d=diff/s=shell/x=exit)? a
OK (438 files copied, 0 skipped)
Configuring install for your environment…amportal…freepbx_engine…done
apply username/password changes to conf files…done
OK
Setting permissions on files…OK
Checking for upgrades…No upgrades found
Generating AMP configs…
Generating Configurations.conf, (if Asterisk is not running, you will get an error
In case of error, start Asterisk and hit the red bar in the GUI to generate the Configuraions.conf files
Generating AMP configs…OK
Restarting Flash Operator Panel…OK
Checking recordings…
Module successfully installed

Module successfully enabled
installed
Checking infoservices…
Module successfully installed

Module successfully enabled
installed
Checking core…
Module successfully installed

Module successfully enabled
installed
Checking framework…
Module successfully enabled
enabled
Checking music…

Module successfully installed

Module successfully enabled
installed
Checking dashboard…
Module successfully installed

Module successfully enabled
installed
Checking featurecodeadmin…
Module successfully installed

Module successfully enabled
installed
Checking customappsreg…
Module successfully installed

Module successfully enabled
installed
Checking voicemail…
Module successfully installed

Module successfully enabled
installed
Please update your modules and reload Asterisk by visiting http://192.168.1.111/admin


  • Note: It’s possible that if you click the red ‘Update Now’ bar BEFORE *
  • updating your modules, your machine will start dropping calls. Ensure *
  • that all modules are up to date BEFORE YOU CLICK THE RED BAR. As long *
  • as this is observed, your machine will be fully functional whilst the *
  • upgrade is in progress. *

do you have any idea for that problem? please give me a hint!
thanks!
Belief Mo