Hello Nick,

I installed Debian-7.3.0 from 3 DVD discks downloaded from:
http://cdimage.debian.org/debian-cd/current/amd64/iso-dvd/

So, this is VERY official Debian repository.
So far, I do not allow updates/installs from Internet,
ONLY from a/m DVD discs.


Trying to install trinity using Synaptic (still from DVD's!)
when I mark for installation kde-core-trinity package
it get marked with RED square, while other dependent packages get
marked with yellow arrow and whole line enlighten with green background.
Then after clicking Apply button message appears:
Could not apply changes! Fix broken packages first.

Next, choosing Edit -> Fix broken packages - another pop-up message:

E: Unable to correct problems, you have held broken packages.
E: Error, pkgProblemResolver::Resolve generated breaks,
   this may be caused by held packages.
E: Unable to correct dependencies

Once more, system installed from 3 DVD discs!!!

Following your suggestion will try with aptitude,
because I'm used to use apt-get most of the time.

Thank you for suggestions.

Best regards.