It looks like you MUST specify an output file. I was getting the same symptoms until I declared one in the Files tab, then I got the output I was looking for.

Also, if you run as root, you get a whole different group of selections! The options that require roof, eg. -sS, don't appear if you aren't able to use them.

Question: How do you get an icon in the Application Menu to "run as root"?
I did the above test from an X Terminal session as root.

Walt