Comet Stacking Problem

[Astrosurf]

My stacked RAWs of Comet Jacques lack the green in the comet, however much I try to pull it out. So I thought I'd stack the JPEGs and overlay them in PS, as they show strong green. But this is what I get. I double-checked in DSS and the purple circle is pretty close around the comet in each image. Can anyone help?

Alexxx

[Bizibilder]

It looks as if you have stacked to give sharp stars and the comet is therefore blurred due to its movement.  Try re-stacking and ensuring you have clicked on the correct button.  You should be OK with RAW images too - the green will show up in post processing.

[Astrosurf]

Thanks Roger, But I've stacked the RAWs twice and in both times the green is lacking. I also made doubly sure the correct option was checked for the JPEGs.