Just set up my first SLR system, and I am having a little problem with the strobe. I have a Canon 400D (Rebel xti), S&S housing, Inon Z-240 connected with five pin Nikonos to the housing. I've been practicing topside, and I can't seem to get the ttl setting to work. I have set the left-hand dial to S-TTL and the right-hand dial to TTL (the 9 o'clock position of the dial). When I do this all of the pictures are very dark...am I doing something wrong?? I am not sure exactly what is wrong...anyone have any ideas?