apt-get install g++-3.4 problem

[<tomas.itsx@centrum.cz>]

 Hi all :)

 I have this problem:
 i try to install g++ but apt-get print this:

# apt-get -f install g++-3.4
Reading package lists... Done
Building dependency tree... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.

Since you only requested a single operation 
it is extremely likely that
the package is simply not installable and a bug report against
that package should be filed.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
  g++-3.4: Depends: libstdc++6-dev (= 3.4.6-5) but it is not going to be installed
E: Broken packages

this is my source.list:

 deb http://ftp.cz.debian.org/debian/ etch main
       deb-src http://ftp.cz.debian.org/debian/ etch main
      
       #deb http://ftp.cz.debian.org/debian/ unstable main
       #deb  http://security.debian.org/  stable/updates main
       #deb http://ftp.cz.debian.org/debian/ testing main
     
       deb http://security.debian.org/ etch/updates main contrib
       deb-src http://security.debian.org/ etch/updates main contrib
 
 please couldnt you suggest what goes wrong?
 thanks 
 itsx