What the heck do they put in jello?!

When I lived in the US I once also attended a baby shower (which is a custom we don't have here in Germany ... at least yet) and for dessert one of the guests brought layered jello. I was totally amazed! It looked simply awesome! I only had it once but it stuck with me. (I was so impressed I remember that I took a photo before I ate my piece.) I thought it probably can't be that hard to make it but I never actually tried it. Overhere in Germany I also never attempted to make it - we simply don't have as many kinds of jello as in the US. In a regular supermarket you find red, green and yellow. That's it. When I read the instructions for layered jello in the blog Fly to my window I came across the idea of adding cool whip, joghurt or sour cream to make the colors paler. So I figured I could end up with at least 6 layers - that sounded good! (Far better than three!) So I was keen to try. (There is another recipe which uses a mixture of cool whip, cream cheese and sour cream to make the color lighter.) So I started by making some red jello, pouring half of it into a chilled dish, mixing the other half with a bit of sour cream ... and put my timer on 15 minutes. This is the time both recipes suggested you should wait. Within 15 minutes the jello in the refrigerator should be firm to the touch - and you should be able to pour the next colour onto it. WELL ... I checked after 15 minutes. But my jello felt not even slightly set! I waited another 15 minutes - again, total liquid. Nothing set! I got a little bit nervous and figured, maybe there is a difference between the american jello-mix and the german "Götterspeise-mix" ... so I consulted the internet (what else?). After a bit of searching I finally found some recipes for layered jello in german (using german jello-mix of course) and discovered - to my shock!!! - that they suggest waiting 6 HOURS !!!! or more before pouring the next colour on top!!! Well, that explains why my jello is not even close to being set ... but it also means that there is no way I will be able to make this dessert for tomorrow ... Rather we will probably be ready to eat it in two days or three ... GREAT!
So I'm really wondering what DO THEY PUT IN JELLO that makes it set so much faster than the german jello mix????

Well, watch out ... in about two or three days there should be photos of my layered jello on this blog ... or of my failed attempt to make layered jello ...