SD cards problems, help?

[RoadTrekker]

First check the copper connectors are not damaged or missing.
Next clean the connectors on the card with alchohol
Next try another SD card reader as it may be faulty or the USB cable
To reformat the card place it in the card reader, connect it to your mac, then go >, Finder > Utilities> Disk Utility> Reformat.
If this does not work then there are loads of SD card revovery programs on the web that you can download and try.

[JustMe]

I´m sure you have checked the tiny write-protected switch on the cards prior to formatting attempt?

Cheers
Chris

[Rfothy]

Yes I have tried all your suggestions guys thanks. I am contacting sandisk themselves too see if they can do anything for me.

[ridetheworld]

How are you connecting them to your iMac? Have you connected them and opened up Disc Utility?

[Rfothy]

Yes I am mate, tried this way. And it works with all other cards except these two

[ridetheworld]

Hmmm,

Assuming you've tried them on a different computer...

Where the cards bought from a reputable vendor (not Amazon)?

There are tones of fakes flying around which have a habit of randomly dying.

The fakes are very convincing and hard to spot. They are rife in S-E Asia.

Good luck with contacting Sandisk and hope they resolve the problem for you.