Ensure that your cache plugins are disabled and flush your browser cache.
If the plugin is not working then most likely an exception had occurred in the plugin that
was caught using the plugin's error handling procedures. To view the
exception, enable the
Debug plugin in the
Miscellaneous Settings section on the
Basic Options tab and check for error
logs in a
jch_optimize file in your logs
The error message should indicate what went wrong but if you're not sure what is means or how to resolve it, then submit a ticket for support and report the exception.
Most likely we would need superuser administrative access to your site and FTP login to resolve this issue so be prepared to provide those. For faster resolution you can consider providing these when you open the ticket.
Access to your website must be provided in the ticket system only! Tickets are private so they can't be viewed by anyone else. Do not post access via email. Also please note that you need an active subscription to submit a ticket.