chkdebnames vs. apt-cache results?

[pll at lanminds.com]

Hi all,

I don't quite understand this:

	$ /usr/share/fai/utils/chkdebnames unstable 80GB_NODE 
	Following packages are not known for the distribution unstable:
	kernel-image-2.4.18
	task-c-dev
	task-debian-devel
	task-debug
	task-devel-common

Yet:
	$ apt-cache search task-c-dev
	task-c-dev - Development in C

	$ apt-cache search task-debug       
	task-debug - Debugging of C, C++, Objective C and friends

	$ apt-cache search task-devel-common
	task-devel-common - Development in various languages

	$ apt-cache search kernel-image-2.4.18
	[...whole long list of stuff snipped...]

The only one which doesn't resolve using apt-cache is task-debian-devel.

Could someone explain to me what's going on here, and what 
chkdebnames is doing vs. what apt-cache is doing?

Thanks,
-- 

Seeya,
Paul