Well, here is the preview of how to add the psnGallery2 Admin in the WP Administration Panel….

Add the following code in the “psnGallery2.php”
function psnGalMenu() {
add_submenu_page('options-general.php', 'psnGallery2', 'psnGallery2', 1, 'psnCPGAdmin.php');
}

and also this to the :

add_action('admin_menu', 'psnGalMenu');

After the update, the code should look like :
function psnGalMenu() {
add_submenu_page('options-general.php', 'psnGallery2', 'psnGallery2', 1, 'psnCPGAdmin.php');
}

global $CONFIG,$pluginURL;

$CONFIG = psnCPGGetConfig();
if ($CONFIG) {
// Initialize the module
psnCPGInit($CONFIG['DEBUGFLAG']);
psnExcludeSQLAlbum();
add_filter('the_content', 'run_CPGxxxx');
add_filter('the_excerpt', 'run_CPGxxxx');
add_filter('comment_text', 'run_CPGxxxx');
add_action('admin_menu', 'psnGalMenu'); // < - New line
}

Et voil