Hi all. Can anyone say what they think went wrong with my blueberry loaf. The recipe didn't ask for any raising agent so I decided to put 1 tsp of bicarb (there was yoghurt in the batter). It was solid over 3/4 from the bottom upwards with just about 1/2 inch of fluffy cake on the top. It looks like baked eggs/omelette ...... very heavy.