When I was using my SB-28 on a Fuji 4900, I'd have to remember to move the power switch to the middle "always on" position rather than the far right "go into standby if you haven't been used" position.
I don't know if it's the same on the D100 or not. You would think there would be some communication between the flash and the camera, even if it's not doing the TTL thing.
Of course I don't ever have this problem on my S2 (just had to say it - sorry!) [img]/ubbthreads/images/graemlins/grin.gif[/img]