sorry to be the bearer of bad news, but when I've gotten that kind of consistency on my cuttings it means they're not going to root. I've always called it slime and I think its the beginning of algae growth.

It looks like blue-green algae to me. Start over.

You said you're using an "aeroponic" system; please elaborate. I use a "cloner" for all my rooted cuttings and the cuttings begin to put on roots in a matter of several days to a week or so. I don't have pictures of my cloner on my Web site any longer (rebuilding the site), but when I do, I'll throw up a post on the forum.

"Woody" rooted cuttings might do better in sand. Just wet the cut ends, dip them in rooting hormone and place them in coarse sand under intermittent misting. That's merely water sprayed on them several times a day to keep things wet and is usually done outside.

Also, watch your temperature; warm is better. 84 degrees F is "hog heaven" for roots.

I rooted some maples one time by just putting them in a glass jar in a window. I used rooting hormone too. I think you'll want to use the new growth though. or use freemans method if your cuts are in the old growth.

You might also want to check for light leaking in to the root zone.