Symptoms
Php-based payment plugin is not displayed in the list of available payment gateways.
Cause
Usually the root cause is some issue with the plugin code. To check it - tail the log /var/log/httpd/payment-sdk.log (on BA application server) when refresh the payment processing page. Further steps depend on the error message you see in the log, usually it is required to contact the plugin developer to correct the issue with the plugin.