I don't know about the ones on Amazon but I bought mine on eBay and it works perfectly. From what I understand you just have to make sure the card is new because it won't work if used in another car for a certain number of miles. There was no way I was paying dealer price and it worked out well for me, but I know you have to be careful.
What year is your 6? Do you have a link or a part # for the SD card you bought?