Install PHPMyAdmin with urpmi

Dear my friends, I've downloaded and installed PHPMyAdmin. I use Apache2 and Mandriva 2009.1. I have defined in the file of '/var/www/phpmyadmin/libraries/config.default.php' this things: " $cfg['Servers'][$i]['user'] = 'root'; $cfg['Servers'][$i]['password'] = 'mypassword'; ". I've done: " grant all on *.* to root identified by 'mypassword'; ". But I still can not login to MySQL from the PHPMyAdmin with root account. If I try login with MySQL-Query-Browser with 'root' and 'mypassword', Im logged-in very properly. What is my mistake actually? Does PHPMyAdmin need to make session on the Apache2? Is it related to "session" and what I should define in '/etc/php.ini'? Please tell me my mistake. Thank you very much in advance.