#34 Fatal error: Call to undefined function: mysql_connect()

[Russ]

I have created a database within mySQL named 'chat',
with a user 'chat' and a relevant password.
The schema seems to have imported OK.
The config.inc.php has been eddited with the following
details:
define('DATABASE_HOST', 'localhost');
define('DATABASE_USER', 'chat');
define('DATABASE_PASSWORD', '********');
define('DATABASE_TABLESPACE', 'chat');

but when I run test.php all I get is a blank page and
when I open the phpopenchat root the following error
occurs
Fatal error: Call to undefined function: mysql_connect()
in /var/www/phpopenchat/include/adodb/drivers/adodb-
mysql.inc.php on line 339

I receive the same error on step 2 of install.php.

thanks in advance for your help

Russ