Do this:

ls -al /dev/cdrom

Should return something like so:

lrwxrwxrwx 1 root root 9 Aug 21 17:05 /dev/cdrom -> /dev/scd0

If so then k3b probably just isn't quite tweaked correctly. Sorry but I don't use GUI's for cd burning so I'm not going to be alot of help beyond here. If you have an .iso on your drive already you can find out if your burner is going to work with linux like so:

cdrecord -v -dummy speed=4 dev=0,0,0 filename.iso

That will carry out the write process but the laser won't be turned on.