Can't do security updates in aptitude for 3 packages

[Csanyi Pal <csanyipal@gmail.com>]

Hi,

my system is Debian GNU/Linux Lenny with linux-image 2.6.26-2-486.

When I run:

$ sudo aptitude

and did update I get that there is three packages for sevurity updates
available. 

When I hit 'g' to did security updates I get message:

--\ Packages being automatically held in their current state (3)
i A  libopenexr6                 1.6.1-3    1.6.1-3+le
i A  linux-image-2.6.26-2-486    2.6.26-17  2.6.26-17l
i A  linux-libc-dev 2.6.26-17    2.6.26-17l

These packages could be upgraded, but they have been kept in their
current state to avoid breaking dependencies.
This group contains 3 packages.

If you select a package, an explanation of its current state will
appear in this space.

libopenexr6 will not be upgraded to version 1.6.1-3+lenny3, to avoid
breaking the following dependencies:

but here isn't list any dependencies! 
That is the case in other two packages too.

What does it mean?
I can't anymore update these packages from this time?

Any advices will be appreciated!

--
Regards,
Paul
http://csanyi-pal.info