NEVER EVER tamper with laser diodes if you do not have the proper knowledge!!!!!
This isn't just a warning for the sake of warning or waiving the finger. Working with laser diodes, ESPECIALLY those from DVD-writers, can be a serious health risk. It wouldn't be the first time that you accidently point it to your eyes or even more common, by suddenly reflecting it to some object in the room...
Laser diodes from DVD-writers are very powerfull, and you can burn stuff with it, including your eyes.
ALWAYS wear SPECIAL laser protecting glasses when dealing with them. Note: a powerfull sunglass doesn't protect you at all, nor does welding glasses; you need special laser protection glasses.
The reason why it doesn't work is very simple, each laser diode requires a specific driver. If you don't have the proper driver for that specific laser diode, it either wont work, or you either will burn out the diode in no-time....
There is a lot of info on the net about this, inlcluding how to build your own drivers. Though, you do need some knowledge to do it properly. I wouldn't advise tampering with lasers if you do not have some electronica knowledge or if you're just a starting electronica hobbiest, even if it sounds "cool".
Be warned of the above! Google is your friend