I recently experienced a problem with the AF-assist lamp on my D300. My set-up was: D300 w/ Sigma 30mm, SB-800 connected via hot shoe cord (SC-28 3rd-party equivalent) set as CLS master, SB-700 set to remote. As the available light disappeared, I realized the AF-assist lamp was not kicking on. I checked the menu on the camera and each flash, to make sure AF-assist was not turned off. In fact, all devices showed the AF-assist light was on. I have looked through the manuals, but I find no clue as to what the issue could have been. I am not experienced using CLS or off-camera flash, so I am wondering if it is some kind of quirk in my set up. Is CLS a red herring? I don't think the Sigma lens should be a factor, I've never had a problem with this lens and the AF-assist lamp. Any insight would be greatly appreciated.