Warning after update to 2.3.6

I have this warning after update the plugin:
Warning: call_user_func_array() expects parameter 1 to be a valid callback, class ‘WP_TMinusCD’ does not have a method ‘myplugin_load_textdomain’ in /web/htdocs/www.perugiavolley.net/home/wp/wp-includes/plugin.php on line 503
wordpres 4.3.1
plugin 2.3.6
thanks

Stefano

https://www.ads-software.com/plugins/jquery-t-countdown-widget/