and here is my etc/apt/source.list :
deb http://ftp.debian.org/debian/ wheezy main contrib non-free
deb-src http://ftp.debian.org/debian/ wheezy main contrib non-free
deb http://ftp.debian.org/debian/ wheezy-updates main contrib non-free
deb-src http://ftp.debian.org/debian/ wheezy-updates main contrib non-free
deb http://security.debian.org/ wheezy/updates main contrib non-free
deb-src http://security.debian.org/ wheezy/updates main contrib non-free
deb http://apt.puredata.info/releases stable main