SD card does not show up

When I connect the camera to my iMac, the card does not show up, nor is it seen by any program (Lightroom, PS etc). It was working yesterday and I can see the pictures using the camera itself.

Any ideas?

Thanks

I'd try another cord first. Can you put the memory into the pc or perhaps in a printer with a slot if the mac doesn't have a slot?
The card must be good if you can see the pics in the camera.
Try another device in the same connect point?

What interfaces does your iMac have? Does it have an SD card slot? A USB port? What other ways can you connect the card? The connection might be the problem. I had a problem with a card recently, and it was the plastic strip that divides the copper connectors on the card. I just ripped it off. Another problem was the spring lead inside the reader not pressing against the card, so I bent it upwards with a pick tool.

It's usually a simple fix.

All-in-all an instructive evening! Trying a different USB port didn't help nor did attaching to my laptop, but a card reader worked; so I thought it has to be a defective cable. So, I get another cable, but still no luck. At this point I am thinking it has to be the mini-port on the camera, which would not be good news since 90% of my work is using the laptop connected to the camera running Helicon Remote. I try again this morning, and it worked! So, at this point tI am still worried that the mini-port might not be 100% reliable, and will have it looked at, but at least I am back in business.

Thanks for the suggestions