Didn't exactly work on my system, but gave me a clue. I used the below to find a valid name for the command
-/dev/sr0 worked here.
sudo lshw -C disk
wodim --devices and
cdrecord --scanbus before finding John's post and those apparently didn't give me a valid block device name.
I typically have trouble using the GUI applications to burn an iso. It's always something. The command line route has been very dependable for me. I like to burn slow to be sure I get a good burn and the command line does that without complaint.
One issue I've had there is with RW media that's not being detected and needs to be blanked before it can be used, and the command line has been dependable there too. Of course you don't want to blank media that's not re-writable....
Here's what I do to get a good burn from the command line. This is done from the directory where the iso is stored to keep it simple.
if RW media is not being detected...
growisofs -Z /dev/sr0=/dev/zero
and the burn -slow burn in this case, run without speed for full speed...
growisofs -dvd-compat -Z /dev/sr0=ubuntu-13.04-desktop-i386.iso -speed=2
Be real, be sober.