I have been home brewing for over 5 years now. I have had great success with making ale,wines and bitters. However I can't seem to get larger right. I nearly always buy kits except wine which I make from concentrate cranberry juice. With larger I make sure I follow all the instruction down to a tea. However it never seems to bubble or comes out flat. I went to the shop for advice, they said try keeping it at 20-25 degrees. I ended up buying a heating belt and a thermometer. However still nothing happend. And again it came out flat with no head. So I've given up now and just sticking to ales which turns out fantastic.