[gryphonslair99]

Originally Posted by rgbii

I just tested the PW's with my Alien Bee's and they work just fine, so I'm pretty sure
this is an issue with my Sigma flash. Would be nice to know if this is just my flash,
or all of the same model.
It seems that in non-ttl slave mode, as long as the contacts are held, the sigma
will continue to flash (no, it's not in the multi-flash mode), while most flashes will
flash just once until the trigger is released and triggered again.

Richard.

Well so much for my idea. I was suspecting you were getting pre-flash from ttl mode. Good luck on finding the problem. You might give a look at Strobist site. Someone may have encountered the same thing there.