Configuration check warning:
The subpart PLACE_LIST_EMPTY is missing in the HTML template file fileadmin/hbm/templates/hbm_tx_seminars_details.tmpl. If you are using a modified HTML template, please fix it. If you are using the original HTML template file, please file a bug report in the bug tracker.
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.