Problem found with function purge_cache_on_post_published

Hi!

First of all the plugin is doing great job, but i find strange problem who i was not able to fix on my own i get error msg during publishing new post/page

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function ‘purge_cache_on_post_published’ not found or invalid function name in /………/wp-includes/class-wp-hook.php on

line 288:
$value = call_user_func_array( $the_[‘function’], array_slice( $args, 0, (int) $the_[‘accepted_args’] ) );

can you please advice

Thank you,
Cheers