r u installing an update or a new instaation of cubase 7.
if installing a new c7 after installation of dvd - Download the latest eLCC from www.elicenser.net
install the latest compatible version of the eLicenser Control Center then follow it should work easily.
make sure you register in mysteinberg and update it to 7.5 too you may be entitled to a free update.
the halion dvd is just wat u need to install no code required.