You did not mention what card you have, or where you bought it. Counterfit cards are very prevalent, look the same and only a expert can tell. Order a quality class 10 card like lexar or sandisk from B&H or Adorama, and you will get the real thing.
Buy from Amazon, only if its actually sold by Amazon. Even then, their buyers may not be very knowledgable about counterfits, but they likely buy direct from the manufacturers, so they are OK.
I'd never trust any card sold on ebay.