hi all. when i type "./install_amp" it's giving an error. i'm using ubuntu and php5. sorry to english.

# cd /usr/src/freepbx/
/usr/src/freepbx# ./install_amp
Checking for PEAR DB..OK
Checking for PEAR Console::Getopt..OK
Checking user..OK
Checking if Asterisk is running..running with PID: 27935..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..Checking for selinux..OK
Connecting to database..OK
Checking current version of AMP..
Fatal error: Call to undefined method DB::Iserror() in /usr/src/freepbx/libfreepbx.install.php on line 105