[Typo3] Extended Calendar - Invalid argument supplied for foreach() in ... /class.tx_calendar_pi1.php on line 724

[Frank]

Hello Ng,

I just installed the extended calendar to check if it's suitable for my 
customers need, but i could not get it to show up at all!

I installed the extension, added the Plugin to an empty page and when 
the page is first rendered I get these PHP warnings:

Warning: Invalid argument supplied for foreach() in 
/srv/www/htdocs/ffs_cms/typo3conf/ext/calendar/pi1/class.tx_calendar_pi1.php 
on line 724

Warning: Cannot modify header information - headers already sent by 
(output started at 
/srv/www/htdocs/ffs_cms/typo3conf/ext/calendar/pi1/class.tx_calendar_pi1.php:724) 
in /srv/www/htdocs/ffs_cms/tslib/class.tslib_fe.php on line 2402

The source just contains the empty calendar <div>-Tag:

<div class="tx-calendar-pi1">
		
</div>

Got typo3 3.7.0 and Extended Calendar 1.1.3 (which actually says: TYPO3 
ver. required: 3.7.2 - 3.7.2!?)

Any Ideas? Thanks for helping!

Frank