Configuration check warning:
The TS setup variable plugin.tx_seminars_pi1.listPID is empty, but needs to be non-empty. This value specifies the page that contains the list of events. If this value is not set correctly, the links in the list view and the back link on the list of registrations will not work. Please correct the TS setup variable plugin.tx_seminars_pi1.listPID in your TS template setup or via FlexForms.
When that is done, please empty the FE cache and reload this page.
The configuration check for this extension can be disabled in the extension manager.