Flat frame box required for darks?

Using I have a sequence that has an automated flat box device selected but not connected.
I have several empty targets plus one target call Flats. The later being the only enabled target. That target has one event of dark frames. When I attempted to start the sequence, SGP complained about the flat box not being connected. Obviously, a flat box is not required to do dark frames. I changed the flat box device to no flat box and then I could run the sequence.