Hello, I have a problem with the installation of the demo content. After activating the plugin displays the message:
Warning: call_user_func_array() expects parameter 1 to be a valid callback, first array member is not a valid class name or object in /home/sellect/domains/ottimoapps.pl/public_html/dev/wp-includes/plugin.php on line 525
Can you halp me?
Kamil