Partitioned my hard drive, now I can't install anything via the dvd drive?

So recently I had to partition my hard drive because it wasn't working so I reinstalled 10.6 (originally 10.5), and now I tried to reinstall my Logic studio and it didn't work, then tried to reinstall my audio interface and it didn't work. I have the installation dvds for both and while the audio interface seemed to work at first my computer would let me run the installed software... Help?