No pics problem

[flytrue]

I have several cameras. I take their card out to view the pics on my Mac laptop. My newest cam is a Gardepro with its own viewer, so I know it has taken pics. Thing is, when I take the card out to load on my laptop the laptop says "No Pictures", like when a card is empty. I've formatted the card as well. I've tried other proven cards and still the same problem. This points to the cam being the problem.
Any ideas?