can't expire certain groups?

In my nightly report, I've been seeing strange errors that expireover 
couldn't expire certain groups.  Anyone have any ideas as to why?  These 
groups are stored in CNFS buffers, but that shouldn't matter, should it?

expireover: could not expire clari.biz.industry.media.releases
expireover: could not expire clari.biz.market.commodities.agricultural
expireover: could not expire clari.biz.market.commodities.misc
expireover: could not expire clari.biz.market.misc
expireover: could not expire clari.biz.misc

It's not limited to the clari hierarchy, but it does seem that the only 
groups that it can't expire begin with 'c'.  Any ideas?
-- 
Donald Roeber
ISC Networking