by Ken Task.
See it says 'to be installed' and build/version is 2012091000 - yes, that is the latest/greatest.
https://moodle.org/plugins/pluginversions.php?plugin=theme_aardvark
shows a download for 2.2 Blackbird (2012050200)
Wonder if the latest/greatest is not compat for some reason and if taking it downward to 2012050200 fixes on your system.
Have you checked apache error logs/php logs to see if there is any hint?
Have you purged caches? (if 2.2 does that!).
Just thinking out loud, really ...
'spirit of sharing', Ken