[TYPO3-project-seminars] PHP Error when saving an event in the Typo3 Backend

[Daniel Bladeck]

Hello,

I have the extension seminars installed on my Typo3 in the version 
4.3.0. I proceeded to the following instructions.

http://typo3.uni-koeln.de/installseminars.html

During installation, there has been no problems. The error occurs when 
saving a new event in my Sys-Folder. The error message is

„Fatal error: Call to a member function isOk() on a non-object in 
/typo3conf/ext/seminars/class.tx_seminars_tcemain.php on line 163“

Environment:
Serversystem FreeBSD 6.2
Apache Version 2.2
MySQL Version 5.0.37
Typo3 Version 4.3.0
PHP Version 5.2.1
Phpinfo
	memory_limit = 256M
	upload_max_filesize = 10M
	register_globals = off


What can I do to remove the error?



Sincerely
Bladeck Daniel