The problem is you formatted your cards in your Mac.
By default, a Mac will format a memory card using the HFS file system, which will not work in a camera.
There is a lot of information here, but if you read through it - I'll tell you how you can fix your problem.
If you attempt to format a memory card on a computer, you must use the following settings:
1. File system: FAT32 (or extFAT for cards 32Gb and above).
2. Allocation Block size: 32Kb
By default, a Mac will not use these settings.
If you format with a Mac, you must use FAT32 or extFAT (which is surprisingly NOT easy to do on a Mac for a lot of people). You can use Disk Utility on a Mac to format the SD card in FAT32, however it will use an allocation block of 4kb, not 32kb - which means the SD card will run slow.
And yes, a Mac will read FAT32 or extFAT from a camera.
Try to format your cards with your camera. If they will not format, it may because the camera does not know how to handle the HFS file system on the Mac.
If that is the case, go to Disk Utility on the MAC, then click on the SD card (make sure it is not pointing to your hard drive or your will wipe the MAC's hard drive clean).
Then select the ERASE button, and then MS-DOS (FAT). This will install FAT32 on your SD card, but with a 4kb allocation block (which will cause the SD card to run slow). However, this should at least let your camera access the card so you can proceed with the next step.
Then put the card back into your camera and format the card. This time the camera should be able to format it. And the camera will change the block size from 4kb to 32kb for the maximum performance.
Incidentally, if you want to format the card correctly in your Mac with the 32kb allocation block, you must use newfs_msdos with the -F 32 switch.
If you don't know how to do that, then I suggest not attempting it as you can damage your Mac's file system.
As I said, not easy for most people.
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Comment for NickP
Hey Nick;
It is a myth that you cannot format a memory card on a computer. While it is often more convenient to format the memory card on the camera, it is not hard at all to do so on a PC.
You can format a SD card on a PC with no problem. You just have to make sure to use FAT32 or extFAT, and a 32kb allocation block.
When you format the card in the camera, it is using the same settings.
And - unless it is a junk camera, the first time you take a photo, the camera will install the DCIM folder along with it's unique subfolder, and typically a temporary index file (which is not essential). This will happen whether or not you format the card in the camera or PC.
The reason camera manufacturers recommend formatting the card in the camera is to ensure the 32kb allocation block is used, as this makes the card more efficient. The default 4kb that the PC will use will make the card run slow. But there is no reason you cannot change the allocation block in the PC.
And, according to JEITA specification, they originally intended a memory card to be used on more than one camera, which is why each camera uses it's own subfolder under DCIM. This allows each camera to peacefully co-exist on the SD card without interfering with each other. But due to the low cost of SD cards these days, this is not often practiced.