Hoping for some ideas. I found the formula on the Martha Stuart site and have tried three times and have had three strikes. My kitchen is cooler than many, with 65F being typical. I followed proofing times and when doing fold and stretch never got more than a glop. No surface tension. That was the first time. Next I proofed and stretched an hour longer. Nada. Last time I heated the oven and did the proofing at about 78F and everything else per formula. Zip. Three strikes. Is my starter (which is quite vigorous at about 6 months of age) burning through the preferment? Suggestions please. I don't want a "zilch". It's a bit frustrating because I've become competent in most other breads, but this eludes me.