phpMyadmin

[Mad Unix]

I have installed phpMyAdmin-2.6.3-pl1 into the Document root
when I call it up http://10.5.1.11/phpMyAdmin-2.6.3-pl1/
I get the following 
"cannot load mysql extension;
please check PHP configuration
Documentation"
I did the modification on config.inc.php host, user, password and
authentication mode "http"

What could be wrong?

Thanks