Site description field is not displaying

I’ve installed the Site Categories plugin and mostly it seems to work fine. Only I can’t get the site description fields to work.

I’m running wordpress 3.4.1 as a subdomain multisite installation. WP super cache is disabled not deactivated and there are harldy any plugins active on the root site.

Here is where the description fields are supposed to show: http://wp.hum.uu.nl/onderwerpen/geesteswetenschappen/

thanks,

Simon