I had Cabernet Sauv grapes picked at an average of 23 brix. Crushed and destemmed, allowing them to ferment in natural yeast. Nothing happened. I used two different hydrometers and specific gravity hovering just about 0, no alcohol % registered. Tried adding yeast, nothing again. Tried to add yeast yet again thinking my batch of yeast was bad. Now they are in car boys, oxygen lock on, nothing happening. what could be wrong? temperature is at about 70 desgress. any help much appreciated.!