Hello,

I have moved your topic to the iCagenda English category of this forum.

So, you may have a jQuery / script conflict on your site with calendar module, and another extension.

Are you on Joomla 2.5 or Joomla 3 ?

You can test your site with Joomla default template to check if issue is not in site template, or try to disable other extensions loaded on the same page (modules, plugins) not-joomla-core, to check which on is giving trouble.
If you want, with an online link, i could check your site code generated to see if i find where the issue could come from.

But, if "auto" mode used, the issue may come from an extensions loading its script file after iCagenda module (so auto control can't detect what happens after) and this issue is typically a Joomla 2.5 common issue (often easily fixed with jQuery Easy Plugin) but if you are on a Joomla 3 website, it could be outdated pratices of one other third-party extension.

Best regards,
Cyril