I was testing an old flash I got with my Mamiya RB67, and trying to get CLS to work. I plugged an SB800 to the X plug of the 180mm f4.5 KL lens using a sync cord. When I fire the shutter, the SB800 fires, but the SB600 doesn't. However, when I test-fire the flash, then the SB600 does fire. What gives? The SB800 was in master mode, the SB600 in slave mode. I know there are other ways to trigger it, but I don't really have money at the moment for radio/optical triggers, I'd like to try to get it done with the equipment I have first before dropping more money down.