Green sardine I think is advertised by Fish Trap as sardine actually. It's got a green back with black flake and a yellowish band, or horizontal stripe with a clear/sparkle belly. Fish it a little bit, and if it doesn't work for ya try something else. No one color is gonna work on all the fish all the time. Maybe your halibut are eatin squid, so a brownish color would work better, or maybe they're eatin perch or ronkies or some other type of forage. Most of the fish around here feed on baitfish cause there's not a lot of squid around here, inshore at least. There's usually a good supply of sardines/smelt/anchovies/mackerel so a lot of the fish are used to feeding on baitfish which is why the green sardine and fastrac work so well. So, all I can tell ya is give it a couple more shots, if it doesn't work, it doesn't work. Find out what they're eatin, screw around with colors, and you'll figure it out. Sometimes half the fun is finding out HOW to catch em.
-Brian