The ISBN system was devised beginning in 1967, and books published prior to then don't have "editions" associated with them. It's very similar with movie, music and video game UPCs. It's also possible that a seller listed an item with us and didn't include an ISBN/UPC with the listing. You'll find items like this by clicking this link.
The Big Bang Theory is the most intelligent and insanely funny TV I have seen since Frazier. I will own all of them. I don't have TV because I can't stand it so I buy DVD's only and this show it awesome.