I think, with Lee's help, we have found the problem with Sii data acquisition in the M16 image. I picked the 19 Sii subs with the highest score and stacked them in DSS
WITHOUT any Master Dark or Master Bias, just Subs alone. When I look at the resulting stack file, there is the signal! Plenty of Sii data there, even in 19 x 60" subs. I stretched it abit in Photoshop and I think I could just plug it into the image now. I believe the DSS dark calibration is scrubbing out the Sii data because it is so close to the floor, or the expected noise. So DSS is definitely doing something I don't want it to do. I might rerun the processing for all my data on M16 without dark calibration and see what I get.
Any DSS experts out there have any idea why inclusion of master darks and master bias in the processing would scrub out my data?
I am posting here a small example of the 19 x 60" Sii sub data, and the larger version on Astrobin.
http://www.astrobin.com/full/251736/0/