I searched a lot on the web and even here, but as you know very well, you can find a lot of documentation for Slackware, that's why I have chosen Slack and I love it, but I just installed Mandrake and I have no manual pages. You know, sometimes you just need a Yahoo Messenger and stuff, but you also want to do some programming...
I get this message:
This is not a permissions problem, because I get the same message when I work with root, too. I already installed all the packages which seem to have any connection with manual pages. Do you have any idea what the problem could be?
Thank you in advance.

If you look in the file /etc/man.config you should see alot of variables with paths to the associated program, e.g.
NROFF /usr/bin/nroff
You should check to make sure those programs are installed and the paths are correct.
which nroff #This will give you the path to nroff on your system.
Then check the MANPATH settings in that file and make sure there are actually some man pages installed where the file says they are. Make sure you have gunzip and bzip2 installed also.