Installing OS X Lion on an iMac
The OS X install disks that used to ship with new Macs were specific to those machines, and can't be used on different models. You're going to have to use Lion Recovery to re-download and install Lion, or go to an Apple Store, they can reinstall it for you if your internet connection isn't sufficient.

It's also likely that the install DVD for your MacBook Pro is for Snow Leopard, any machine that shipped with Lion didn't come with install media, just a recovery partition.