Hello.
I'm having trouble with a universal media card reader.
It's one of these USB plug-in units, with a few slots, for different memory card types.
I use SD cards, in my digital camera.
When I take pictures I can see them o the SD card, which shows up as "sd1"
The trouble starts when I try to write to this card.
I can't copy any files to the SD card - I get the Konqueror error "could not write to media/disk filename.jpg"
I checked the permissions - I was ok to write.
"owner can write and modify content"
"group - can view content"
I tried to change the permissions for the group - it wouldn't allow me.
I tried it as root - would not allow me to change permissions... I get the same Konqueror error - "could not change permissions for media/disk.."

help!

The reader work just fine in Windoze.
Oh, and I tried five different SD cards.
I use Mandriva 2008

Could you indicate whether you use kde, gnome or another desktop environment. And which version. KDE 3.5 is a lot different from KDE 4.0.
In KDE 3.5, when the icon comes up in the desktop, you can right click on it and select properties. In the "mounting" tab, you can select "Mount as user" to have the device mount owned by that user, giving the user write access.

Also check the read only tab on the SD cards.

Also, be careful that you eject them properly. If the filesystem is corrupt you won't be able to write to them. Sometimes a defect will be noticed after mounting and the device will be remounted read-only.

my KDE is rev. 3.5.7 and so is Konqueror.
There is no "mount as user" option in the properties.
The cards I used don't even have the 'write-protect' switch.
I'll try to format them in Windoze. That may do the trick..

I just started a KDE 3.5 session. It is in the Mounting tab of properties. I right clicked on the sysinfo:/ page in konqueror over the device.

To display the icon on the desktop, I needed to right-click on the desktop. Select configure. Select "Behavior". Then I enabled "Show Device Icons".

Make sure you don't boot up with the "noacpi" boot option. Make sure the udevd and hald daemons are running:
ps -u root | egrep '(udev|hal)'

Did it automount under /media? If so enter:
ls -ld /media/*

Post the results. This will show the permissions.

Try the "touch" command to create a file inside. Example:
touch /media/expansion/testfile

If there is an error post the error message. Also look at any kernel messages just after the error:
sudo tail /var/log/messages

Sometimes a kernel message will give more information on the exact cause.

I got it to work by shredding the SD card:

su
[root password]
shred -n 1 -z -v /dev/sda1

Then I formatted the card
I can write and read now
I guess it was corrupted structure of the card, just like you suggested

thanks for your help!

Don't use shred on an SD card. You can use dd to zero it out, but you want to limit the number of writes to an SD card.