Packages have been kept back -- What to do?

[Kipton Moravec]

Why have these packages been kept back?
What does kept back mean?
How do I fix it?

kip at Red:~ $ sudo apt-get dist-upgrade
Password:
Reading package lists... Done
Building dependency tree... Done
Calculating upgrade...Done
The following packages have been kept back:
  gdk-imlib1 libkrb5-17-heimdal libopenal0 moagg
0 upgraded, 0 newly installed, 0 to remove and 4 not upgraded.

I get this type of error whenever I do a security update. The message
says do sudo apt-get dist-upgrade to fix it. As you can see it does not
fix the problem.

So now what?

Kip
-- 
Kipton Moravec <kip at kdream.com>