"An error occurred while processing your transaction: Unable to process transaction. Possible restrictKey mismatch."

[rody4717]

I suspect the CVV is just invalid (usual case these days if you use autoshop to buy them) or low bal/incorrect billing address or your IP/system isn't clean and is detected.
The error message suggests that it could be store's problem as well but it is not likely. Maybe some one else knows better, I've never seen this exact message with any merchant I know of.