There is a bug in Fantastico for PHPList installation. Whenever you install PHPList from Fantastico, you will need to edit your config.php.
You will need to put # before following line in your config.php:
define("PLUGIN_ROOTDIR","/tmp");
And remove # from the below line in your config.php:
define("PLUGIN_ROOTDIR","plugins");
Kailash
Thank you kailash, you helped us very much.