"category__and" argument to display only if in multiple categories?

Hi, great plug-in, good documentation too. I’m trying to display events only if they are in 2 certain categories, like you can do with a regular wordpress query. I tried:

<?php echo EM_Events::output(array('scope'=>'year', 'category' => "2,5", 'orderby'=> 'event_start_date', 'limit'=>0, 'pagination'=>1)); ?>
which displays all posts from both categories, instead of only posts that are in both categories.
I also tried
<?php echo EM_Events::output(array('scope'=>'year', 'category__and' => array(2,5), 'orderby'=> 'event_start_date', 'limit'=>0, 'pagination'=>1)); ?>
but to no avail. Can you tell me how please?

Thanks!

http://wordpress.org/extend/plugins/events-manager/