I'm using Lion (10.7.3) on a mid-2010 MacBook Pro. I just got a 32GB SD card and formatted it with my camera. I'd like to transfer some files onto it from my computer, but the card seems to be read-only when I access it in Finder. And in Disk Utility, all options are grayed out so I can't reformat the card.


I found this KB article which seems to describe the problem, but the solution doesn't work:
$ diskutil partitiondisk disk1 JHFS+ newdisk 100%
Started partitioning on disk1
Unmounting disk
Error: -69877: Couldn't open device
What's going on and how can I get around it?
Edit: yes, I already checked the physical lock switch on the card!