Target disk mode only shows installation DVD, not hard-disk

Last night my mid-2009 MacBook Pro crashed/froze (a few seconds after opening the laptop to work on it). I turned it off with the power button and tried to restart it. It showed a folder icon with a question mark on a grey screen, so I tried restarting while holding the option-key. After that didn't work, I restarted with the shift-key (safe mode).

That wouldn't work either, so I put the MacOSX installation DVD that came with my Mac in and started up while pressing c. In disk utility it didn't show my hard-disk, just the installation DVD, so I put it in target disk mode with a newer MacBook Pro. This seemed to work, but my hard-disk didn't show up on the other computer. The installation DVD did show up, though. What could be wrong with my hard-disk? Is there any chance for me to get my data back?

Thanks in advance!

Ziska