Coupon Creator Problem WordPress Version 3.4.2.1

Hi, I updated WordPress and other plugins and then I’m having an admin login issue, but the coupon page works fine on the front end. What happened? How can I fix it? I’ll post the error codes WordPress is reporting. Thanks for your reply.

Un errore di E_ERROR è stato causato nella linea 358 del file /var/www/vhosts/vacanzelandia.com/shop.vacanzelandia.com/wp-content/plugins/coupon-creator/plugin-engine/vendor/lucatume/di52/src/tad/DI52/Container.php. Messaggio di errore: Uncaught RuntimeException: Error while making 'admin.assets': Class admin.assets does not exist in /var/www/vhosts/vacanzelandia.com/shop.vacanzelandia.com/wp-content/plugins/coupon-creator/plugin-engine/vendor/lucatume/di52/src/tad/DI52/Container.php:358 Stack trace: #0 /var/www/vhosts/vacanzelandia.com/shop.vacanzelandia.com/wp-content/plugins/coupon-creator/plugin-engine/vendor/lucatume/di52/src/tad/DI52/Container.php(283): tad_DI52_Container->resolve() #1 /var/www/vhosts/vacanzelandia.com/shop.vacanzelandia.com/wp-content/plugins/coupon-creator/plugin-engine/src/Pngx/Container.php(181): tad_DI52_Container->make() #2 /var/www/vhosts/vacanzelandia.com/shop.vacanzelandia.com/wp-content/plugins/coupon-creator-pro/src/Cctor/Admin/Bulk_Edits.php(64): pngx() #3 /var/www/vhosts/vacanzelandia.com/shop.vacanzelandia.com/wp-includes/class-wp-hook.php(324): Cctor__Coupon__Pro__Admin__Bulk_Edits->bulk_edit_enqueue_style_scripts() #4 /var/www/vhosts/vacanzelandia.com/shop.vacanzelandia.com/wp-includes/class-wp-hook.php