DVD drive Problem

Ok so I'm trying to reinstall Vista32bit on my Dell XPS M1210. So I go to plug in the reinstallation DVD and the drive won't recognize it. It will play other DVDs including the driver DVD and other CDs, Just NOT the reinstall DVD. Whats going on here?

Hello, have you used the Bios settiings to change boot order first : http://www.vistax64.com/tutorials/205005-boot-priority-change.html