Migrating iPhoto Library
Are you trying to import your old library into a new one? If so that's now what you want do to. You'll end up with all of the image files of the old library, originals, modified, thumbnails, faces, etc. imported as if they were all original files and you'll lose all events, albums, etc.
Try connecting the two Macs via Target Disk Mode (with the iMac in the disk mode) and see if you can drag the iPhoto library package from the iMac to the Pictures folder on the Macbook.