CDDB works on one Mac but not another for the same CD!

We have a MacBook Pro and an iMac. Both are running on Snow Leopard version 10.6.7 with iTunes 10.2.2 installed. I have manually loaded an audiobook into the MacBook Pro but cannot retrieve the track titles from CDDB. I get the error: CDDB is not available for some of these items. What I don't understand is that I moved these exact same tracks from my MacBook onto my iMac (where I sync my iPod) and was able to retrieve the information with CDDB! So I know it's not an issue with the track information not being available. I know there has to be some setting that I've not correctly selected on my MacBook Pro...I've gone item by item through my preferences and just can't figure out where the two are different. Any suggestions?