Usually caused by a jQuery or javascript clash - are there any errors in your web browser error console?

Thanks for your reply. No, there are no errors in the console. Where can I start looking for clashes?

Can you give me the URL to look at? If its private put it on the 'site details' tab below

Yes, it is private. Please find a login below. Thank you!

I think the CB User needs to be activated.

Sorry, created Joomla user instead of CB user

Still getting the same message

Die Registrierung ist nicht vollständig! Weitere Hinweise wurden an die angegebene E-Mail-Adresse geschickt. Wenn keine E-Mail eingetroffen sein sollte, bitte den Spam-Filter prüfen. Wenn das nicht weiterhilft, bitte erneut die Anmeldeprozedur durchführen, damit eine neue E-Mail mit Instruktionen zugeschickt werden kann.

Sorry. I did it again, double checked and logged in, works for me. Please try again.

Your version of JEvents was out of date - I updated it and now it works ok.

Thanks for your support. Updating was probably well intentioned, but completely broke it - not obvious at first sight, but many details wrong after update. Fortunately I have a recent backup so could restore quickly. At least I know better where to look for the issue now.