I bought CS5 extended from a seller on Ebay
Unfortunately, that usually bodes badly for the ability to Activate your software.
While I feel that there might be a very few legit copies of Adobe programs on eBay, the vast majority seem to be bogus - pirated - hacked, or just an excuse to get one's credit card info for later use, or resale on the black market.
The box was sealed from Adobe, has the genuine Adobe sticker, its all legitimate.
There is a lot of bogus packaging out there, and some years ago, even certified Adobe resellers were blind-sided by pirated copies, that looked perfect, from China.
Contact the seller and demand either a refund, or a working S/N.
Good luck, and hope that you DID buy a legit copy, and that the seller CAN provide you with a working S/N.
Not necessarily. Just because it looks legitimate does not mean it is. Counterfeiters can easily make it look authentic. See posts about this all the time about PS purchased from Ebay.
Call Adobe on weekday and have them check serial number. They will say whether it is valid or not.
Thanks for the info guys. It might be a pirate copy then. If so, it looks like a perfect one...