ScanDisk CF - No access to card - 1Dx

Hey
I bought two ScanDisk Extreme PRO 64gb 160mb/s cards for my 1Dx. However one of the cards are not working, no matter wich slot i put it in i get the error message "No access to card" tried it on my 7D and the same message.
However it works fine on my computer. I am able to access the card and copy files on it.

Anyone have a clue what i can be wrong? i have tried to format the card on my computer but still the same error on the camera

Update:
After formating the card 2-3 more times on the computer it finaly worked! However, can i be sure that this card wont fail in the future?

Not enough to go on as far as making suggestions. However, first thing you should be doing is doing the format operation in camera, as opposed to doing it with a PC. The format operation in camera sets up a particular directory structure. My own experimentation indicates that at least on what I own (60D & 80D), if I format in a PC, the camera sets up the structure at the intial exposure on the card. That may or may not be true with all DSLR's so IMO best play safe, do it in camera.

If you are absolutely certain you have moved or copied the images off the card, then toggle the option to do a low level format. Just keep in mind that nothing will be recoverable after a low level format. Card content is essentially gone.

They have good warranty, no reason to debug yourself and risk looking data. I would suggest get it replaced.