root@aspic:~/GELLY# apt-get update
Get:1 http://ftp.de.debian.org stable Release.gpg [189B]
Hit http://ftp.de.debian.org stable Release
Ign http://ftp.de.debian.org stable/main Packages
Ign http://ftp.de.debian.org stable/contrib Packages
Ign http://ftp.de.debian.org stable/non-free Packages
Hit http://ftp.de.debian.org stable/main Packages
Hit http://ftp.de.debian.org stable/contrib Packages
Hit http://ftp.de.debian.org stable/non-free Packages
Get:2 http://security.debian.org stable/updates Release.gpg [189B]
Hit http://security.debian.org stable/updates Release
Ign http://security.debian.org stable/updates/main Packages
Ign http://security.debian.org stable/updates/contrib Packages
Ign http://security.debian.org stable/updates/non-free Packages
Hit http://security.debian.org stable/updates/main Packages
Hit http://security.debian.org stable/updates/contrib Packages
Hit http://security.debian.org stable/updates/non-free Packages
Fetched 378B in 2s (180B/s)

root@aspic:~/GELLY# apt-get install libgd2-dev
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:
  libgd2-dev: Depends: libgd2-noxpm-dev (>= 2.0.4-2) but it is not going to be installed or
                       libgd2-xpm-dev (>= 2.0.4-2) but it is not going to be installed
E: Broken packages
root@aspic:~/GELLY# dselect
Reading package lists... Done
Building dependency tree... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Do you want to erase any previously downloaded .deb files? [Y/n]
Press enter to continue.

running dpkg --pending --configure ...
running dpkg --pending --remove ...
root@aspic:~/GELLY# apt-get install libgd2-noxpm-dev
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:
  libgd2-noxpm-dev: Depends: libpng12-0-dev
E: Broken packages
root@aspic:~/GELLY# apt-get install libpng12-0-dev
Reading package lists... Done
Building dependency tree... Done
Note, selecting libpng12-dev instead of libpng12-0-dev
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:
  libpng12-dev: Depends: libpng12-0 (= 1.2.8rel-1) but 1.2.8rel-5 is to be installed
E: Broken packages
root@aspic:~/GELLY# apt-get install libpng12-0
Reading package lists... Done
Building dependency tree... Done
libpng12-0 is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
root@aspic:~/GELLY#