Funnily, my newly vfat-formatted USB stick is automatically mounted when I plug it in, nautilus sees it, I can access it, I can see the permissions in the nautilus right click dialog (755), I can create and delete files from command line:

 $ touch/run/mount/christian/XXXX-XXXX/anyfile.txt

I can even move files (with Del key) into trash from within nautilus.

But when I try to create a new directory,a new file, or copy a file to that stick **using nautilus** in Arch linux, I just get the error message (German):

 Fehler beim Kopieren nach »Datenträger 4,0 GB«.
 Das Ziel ist schreibgeschützt

Which means: **Error copying to »Storage device 4,0 GB - Target is read-only«

I don't get it. It can't be on OS layer. I can touch, delete, renamy, copy anything on the command line. It must be something GNOME restricts. Is it necessary to be in a group in Arch/GNOME to write to USB devices? And why can I delete files (Move to trash **and** delete is possible from within nautilus!)
I am in the following groups:

 sys lp wheel network video audio storage power libvirt users