Yes, this is because you don't have updated, the fix is in 2.1.7...

BUT !

IMPORTANT for YOU :

First, update your joomla to 2.5.11 (it is an important security update, and 2.5.9 has vulnerabilities!)

Secundly, update iCagenda to the latest version 2.1.12 (in a few hours, i will add the 2.1.13 with a little fix for class suffix when error reporting is set on "on")

And a other thing you can do, and may be really useful for the future : update your php version to at least 5.3 !
How to do that ? You can ask your hoster (the easier way, and sometimes they do it themselves!), or search on joomla.org forum
Why it is important ? : Php 5.3 is the minimum recommanded for Joomla 2.5 and the minimum required for Joomla 3. More and more extensions are using now only php 5.3 as minimum (iCagenda is developped under php 5.3+ but i've still added some code for php 5.2 (but with php 5.2 some settings could not work as describe in documentation)

PHP 5.2 is 2 years old without updates, and since php 5.3 new features help developper to do new things working better, but this new features aren't compatible with php 5.2.


Hope this information will help you to use Joomla in a better way

Regards,
Lyr!C