welcome to the mad world of homebrewing!, gotta ask, did you keep both brewbelts switched on during fermentation? look into making your own temp controller with a little gizmo called an stc-1000, cheap at around a tenner and with it you will get more reliable brews, it controls not just the heating(in winter) of the homebrew but the cooling(in summer-with a fridge, normally in the garage) makes the yeast work properly at the right temp, oh and be careful! this hobby bites you before you know it and there is no way back lol