Norton AntiVirus 2010 activation issue

I receive the following when I attempt to activate my product:  "This is not a valid product key and cannot be used to activate this product".

 

Any ideas as to why I'd get this message?  I bought this product probably six months ago, and have physical CD and product key, which I know that I'm entering correctly.

 

Any advice is appreciated.

Hi dputlak,

 

Does the product key correspond to the product - are you installing the product that is on the CD or are you using the key to renew an already installed program?  Did you buy the product from a retailer or from a seller on eBay?