Calendar Base Error

Message: Missing or wrong parameter. The event you are looking for could not be found.

Note: Please verify your URL parameter: tx_cal_controller[uid]

URL:http://gruene-unterfranken.de/termine/cal/event//tx_cal_phpicalendar/2019/09/21/oeffentliche_raeume_in_stadt_und_land_qualitaeten_chancen_und_herausforderungen/